diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8568cd5feed..bc8af9e6322 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -6258,13 +6258,20 @@ namespace ts {
                     targetType = typeToString(target, /*enclosingDeclaration*/ undefined, TypeFormatFlags.UseFullyQualifiedType);
                 }
 
+                // check if trying to relate primitives to the boxed/apparent backing types.
+                if ((sourceType === "Number" && targetType === "number") ||
+                    (sourceType === "String" && targetType === "string") ||
+                    (sourceType === "Boolean" && targetType === "boolean")) {
+                        reportError(Diagnostics._0_is_a_primitive_type_while_1_is_a_boxed_object_Prefer_using_0_when_possible, targetType, sourceType);
+                }
+
                 if (!message) {
                     message = relation === comparableRelation ?
                         Diagnostics.Type_0_is_not_comparable_to_type_1 :
                         Diagnostics.Type_0_is_not_assignable_to_type_1;
                 }
 
-                reportError(message, sourceType, targetType);
+                reportError(message, sourceType, targetType);               
             }
 
             // Compare two types and return
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 6210a20afa6..fb8bc21ec95 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -1955,6 +1955,10 @@
         "category": "Error",
         "code": 2691
     },
+    "'{0}' is a primitive type while '{1}' is a boxed object. Prefer using '{0}' when possible.": {
+        "category": "Error",
+        "code": 2692
+    },
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
         "code": 4000
diff --git a/tests/baselines/reference/apparentTypeSubtyping.errors.txt b/tests/baselines/reference/apparentTypeSubtyping.errors.txt
index e1a53ef6a73..c19cfa44360 100644
--- a/tests/baselines/reference/apparentTypeSubtyping.errors.txt
+++ b/tests/baselines/reference/apparentTypeSubtyping.errors.txt
@@ -1,6 +1,7 @@
 tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSubtyping.ts(9,7): error TS2415: Class 'Derived<U>' incorrectly extends base class 'Base<string>'.
   Types of property 'x' are incompatible.
     Type 'String' is not assignable to type 'string'.
+      'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
 
 
 ==== tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSubtyping.ts (1 errors) ====
@@ -17,6 +18,7 @@ tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSubtypi
 !!! error TS2415: Class 'Derived<U>' incorrectly extends base class 'Base<string>'.
 !!! error TS2415:   Types of property 'x' are incompatible.
 !!! error TS2415:     Type 'String' is not assignable to type 'string'.
+!!! error TS2415:       'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
         x: String;
     }
     
diff --git a/tests/baselines/reference/apparentTypeSupertype.errors.txt b/tests/baselines/reference/apparentTypeSupertype.errors.txt
index 5fe5c92a5b3..b7195557e8d 100644
--- a/tests/baselines/reference/apparentTypeSupertype.errors.txt
+++ b/tests/baselines/reference/apparentTypeSupertype.errors.txt
@@ -2,6 +2,7 @@ tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSuperty
   Types of property 'x' are incompatible.
     Type 'U' is not assignable to type 'string'.
       Type 'String' is not assignable to type 'string'.
+        'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
 
 
 ==== tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSupertype.ts (1 errors) ====
@@ -19,5 +20,6 @@ tests/cases/conformance/types/typeRelationships/apparentType/apparentTypeSuperty
 !!! error TS2415:   Types of property 'x' are incompatible.
 !!! error TS2415:     Type 'U' is not assignable to type 'string'.
 !!! error TS2415:       Type 'String' is not assignable to type 'string'.
+!!! error TS2415:         'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
         x: U;
     }
\ No newline at end of file
diff --git a/tests/baselines/reference/arrayLiterals3.errors.txt b/tests/baselines/reference/arrayLiterals3.errors.txt
index 8e6c7eccf81..eb0c6dc51b7 100644
--- a/tests/baselines/reference/arrayLiterals3.errors.txt
+++ b/tests/baselines/reference/arrayLiterals3.errors.txt
@@ -18,6 +18,7 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
       Types of parameters 'items' and 'items' are incompatible.
         Type 'Number' is not assignable to type 'string | number'.
           Type 'Number' is not assignable to type 'number'.
+            'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
 
 
 ==== tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts (6 errors) ====
@@ -81,4 +82,5 @@ tests/cases/conformance/expressions/arrayLiterals/arrayLiterals3.ts(34,5): error
 !!! error TS2322:       Types of parameters 'items' and 'items' are incompatible.
 !!! error TS2322:         Type 'Number' is not assignable to type 'string | number'.
 !!! error TS2322:           Type 'Number' is not assignable to type 'number'.
+!!! error TS2322:             'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
     
\ No newline at end of file
diff --git a/tests/baselines/reference/assignFromBooleanInterface.errors.txt b/tests/baselines/reference/assignFromBooleanInterface.errors.txt
index 4b06603a9bf..f5c92a47569 100644
--- a/tests/baselines/reference/assignFromBooleanInterface.errors.txt
+++ b/tests/baselines/reference/assignFromBooleanInterface.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface.ts(3,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
+  'boolean' is a primitive type while 'Boolean' is a boxed object. Prefer using 'boolean' when possible.
 
 
 ==== tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface.ts(3
     x = a;
     ~
 !!! error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
+!!! error TS2322:   'boolean' is a primitive type while 'Boolean' is a boxed object. Prefer using 'boolean' when possible.
     a = x;
\ No newline at end of file
diff --git a/tests/baselines/reference/assignFromBooleanInterface2.errors.txt b/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
index c03eab60c74..bfbf56eec5a 100644
--- a/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
+++ b/tests/baselines/reference/assignFromBooleanInterface2.errors.txt
@@ -3,6 +3,7 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(
     Type '() => Object' is not assignable to type '() => boolean'.
       Type 'Object' is not assignable to type 'boolean'.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(19,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
+  'boolean' is a primitive type while 'Boolean' is a boxed object. Prefer using 'boolean' when possible.
 tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(20,1): error TS2322: Type 'NotBoolean' is not assignable to type 'boolean'.
 
 
@@ -33,6 +34,7 @@ tests/cases/conformance/types/primitives/boolean/assignFromBooleanInterface2.ts(
     x = a; // expected error
     ~
 !!! error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
+!!! error TS2322:   'boolean' is a primitive type while 'Boolean' is a boxed object. Prefer using 'boolean' when possible.
     x = b; // expected error
     ~
 !!! error TS2322: Type 'NotBoolean' is not assignable to type 'boolean'.
diff --git a/tests/baselines/reference/assignFromNumberInterface.errors.txt b/tests/baselines/reference/assignFromNumberInterface.errors.txt
index 0c8c4a5f5ac..e68ec76f68f 100644
--- a/tests/baselines/reference/assignFromNumberInterface.errors.txt
+++ b/tests/baselines/reference/assignFromNumberInterface.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/primitives/number/assignFromNumberInterface.ts(3,1): error TS2322: Type 'Number' is not assignable to type 'number'.
+  'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
 
 
 ==== tests/cases/conformance/types/primitives/number/assignFromNumberInterface.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/conformance/types/primitives/number/assignFromNumberInterface.ts(3,1
     x = a;
     ~
 !!! error TS2322: Type 'Number' is not assignable to type 'number'.
+!!! error TS2322:   'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
     a = x;
\ No newline at end of file
diff --git a/tests/baselines/reference/assignFromNumberInterface2.errors.txt b/tests/baselines/reference/assignFromNumberInterface2.errors.txt
index 85639cdeeaf..5cae4654760 100644
--- a/tests/baselines/reference/assignFromNumberInterface2.errors.txt
+++ b/tests/baselines/reference/assignFromNumberInterface2.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/primitives/number/assignFromNumberInterface2.ts(24,1): error TS2322: Type 'Number' is not assignable to type 'number'.
+  'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
 tests/cases/conformance/types/primitives/number/assignFromNumberInterface2.ts(25,1): error TS2322: Type 'NotNumber' is not assignable to type 'number'.
 
 
@@ -29,6 +30,7 @@ tests/cases/conformance/types/primitives/number/assignFromNumberInterface2.ts(25
     x = a; // expected error
     ~
 !!! error TS2322: Type 'Number' is not assignable to type 'number'.
+!!! error TS2322:   'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
     x = b; // expected error
     ~
 !!! error TS2322: Type 'NotNumber' is not assignable to type 'number'.
diff --git a/tests/baselines/reference/assignFromStringInterface.errors.txt b/tests/baselines/reference/assignFromStringInterface.errors.txt
index 6ec8afad120..80268f4b06a 100644
--- a/tests/baselines/reference/assignFromStringInterface.errors.txt
+++ b/tests/baselines/reference/assignFromStringInterface.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/primitives/string/assignFromStringInterface.ts(3,1): error TS2322: Type 'String' is not assignable to type 'string'.
+  'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
 
 
 ==== tests/cases/conformance/types/primitives/string/assignFromStringInterface.ts (1 errors) ====
@@ -7,4 +8,5 @@ tests/cases/conformance/types/primitives/string/assignFromStringInterface.ts(3,1
     x = a;
     ~
 !!! error TS2322: Type 'String' is not assignable to type 'string'.
+!!! error TS2322:   'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
     a = x;
\ No newline at end of file
diff --git a/tests/baselines/reference/assignFromStringInterface2.errors.txt b/tests/baselines/reference/assignFromStringInterface2.errors.txt
index 4e09eb6eacb..d20bdaaba32 100644
--- a/tests/baselines/reference/assignFromStringInterface2.errors.txt
+++ b/tests/baselines/reference/assignFromStringInterface2.errors.txt
@@ -1,4 +1,5 @@
 tests/cases/conformance/types/primitives/string/assignFromStringInterface2.ts(47,1): error TS2322: Type 'String' is not assignable to type 'string'.
+  'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
 tests/cases/conformance/types/primitives/string/assignFromStringInterface2.ts(48,1): error TS2322: Type 'NotString' is not assignable to type 'string'.
 
 
@@ -52,6 +53,7 @@ tests/cases/conformance/types/primitives/string/assignFromStringInterface2.ts(48
     x = a; // expected error
     ~
 !!! error TS2322: Type 'String' is not assignable to type 'string'.
+!!! error TS2322:   'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
     x = b; // expected error
     ~
 !!! error TS2322: Type 'NotString' is not assignable to type 'string'.
diff --git a/tests/baselines/reference/nativeToBoxedTypes.errors.txt b/tests/baselines/reference/nativeToBoxedTypes.errors.txt
new file mode 100644
index 00000000000..c471e6b0e7b
--- /dev/null
+++ b/tests/baselines/reference/nativeToBoxedTypes.errors.txt
@@ -0,0 +1,29 @@
+tests/cases/compiler/nativeToBoxedTypes.ts(3,1): error TS2322: Type 'Number' is not assignable to type 'number'.
+  'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
+tests/cases/compiler/nativeToBoxedTypes.ts(7,1): error TS2322: Type 'String' is not assignable to type 'string'.
+  'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
+tests/cases/compiler/nativeToBoxedTypes.ts(11,1): error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
+  'boolean' is a primitive type while 'Boolean' is a boxed object. Prefer using 'boolean' when possible.
+
+
+==== tests/cases/compiler/nativeToBoxedTypes.ts (3 errors) ====
+    var N = new Number();
+    var n = 100;
+    n = N;
+    ~
+!!! error TS2322: Type 'Number' is not assignable to type 'number'.
+!!! error TS2322:   'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
+    
+    var S = new String();
+    var s = "foge";
+    s = S;
+    ~
+!!! error TS2322: Type 'String' is not assignable to type 'string'.
+!!! error TS2322:   'string' is a primitive type while 'String' is a boxed object. Prefer using 'string' when possible.
+    
+    var B = new Boolean();
+    var b = true;
+    b = B;
+    ~
+!!! error TS2322: Type 'Boolean' is not assignable to type 'boolean'.
+!!! error TS2322:   'boolean' is a primitive type while 'Boolean' is a boxed object. Prefer using 'boolean' when possible.
\ No newline at end of file
diff --git a/tests/baselines/reference/nativeToBoxedTypes.js b/tests/baselines/reference/nativeToBoxedTypes.js
new file mode 100644
index 00000000000..074b39fa08d
--- /dev/null
+++ b/tests/baselines/reference/nativeToBoxedTypes.js
@@ -0,0 +1,23 @@
+//// [nativeToBoxedTypes.ts]
+var N = new Number();
+var n = 100;
+n = N;
+
+var S = new String();
+var s = "foge";
+s = S;
+
+var B = new Boolean();
+var b = true;
+b = B;
+
+//// [nativeToBoxedTypes.js]
+var N = new Number();
+var n = 100;
+n = N;
+var S = new String();
+var s = "foge";
+s = S;
+var B = new Boolean();
+var b = true;
+b = B;
diff --git a/tests/baselines/reference/primitiveMembers.errors.txt b/tests/baselines/reference/primitiveMembers.errors.txt
index da8b75f9bc5..24f02486d00 100644
--- a/tests/baselines/reference/primitiveMembers.errors.txt
+++ b/tests/baselines/reference/primitiveMembers.errors.txt
@@ -1,5 +1,6 @@
 tests/cases/compiler/primitiveMembers.ts(5,3): error TS2339: Property 'toBAZ' does not exist on type 'number'.
 tests/cases/compiler/primitiveMembers.ts(11,1): error TS2322: Type 'Number' is not assignable to type 'number'.
+  'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
 
 
 ==== tests/cases/compiler/primitiveMembers.ts (2 errors) ====
@@ -18,6 +19,7 @@ tests/cases/compiler/primitiveMembers.ts(11,1): error TS2322: Type 'Number' is n
     n = N;  // should not work, as 'number' has a different brand
     ~
 !!! error TS2322: Type 'Number' is not assignable to type 'number'.
+!!! error TS2322:   'number' is a primitive type while 'Number' is a boxed object. Prefer using 'number' when possible.
     N = n; // should work
     
     var o: Object = {}
diff --git a/tests/cases/compiler/nativeToBoxedTypes.ts b/tests/cases/compiler/nativeToBoxedTypes.ts
new file mode 100644
index 00000000000..6cd51251b06
--- /dev/null
+++ b/tests/cases/compiler/nativeToBoxedTypes.ts
@@ -0,0 +1,11 @@
+var N = new Number();
+var n = 100;
+n = N;
+
+var S = new String();
+var s = "foge";
+s = S;
+
+var B = new Boolean();
+var b = true;
+b = B;
\ No newline at end of file