diff --git a/Expecto.Tests/Tests.fs b/Expecto.Tests/Tests.fs
index 09d60a54..8a0be140 100644
--- a/Expecto.Tests/Tests.fs
+++ b/Expecto.Tests/Tests.fs
@@ -449,7 +449,7 @@ let expecto =
         ]
       ]
 
-      testList "string isempty" [
+      testList "string isnotempty" [
         testCase "when string is not empty" <| fun _ ->
           Expect.isNotEmpty "dede" "should pass because string is not empty"
         
@@ -458,6 +458,19 @@ let expecto =
         ) |> assertTestFails
       ]
 
+      testList "string isnotwhitespace" [
+        testCase "when string is not whitespace" <| fun _ ->
+          Expect.isNotEmpty "  dede  " "should pass because string is not whitespace"
+        
+        testCase "when string is empty" (fun _ ->
+          Expect.isNotEmpty "" "should fail because string is empty"
+        ) |> assertTestFails
+
+        testCase "when string is whitespace" (fun _ ->
+          Expect.isNotEmpty "             " "should fail because string is whitespace"
+        ) |> assertTestFails
+      ]
+
       testList "string contain" [
         testCase "pass" <| fun _ ->
           Expect.stringContains "hello world" "hello" "String actually contains"
diff --git a/Expecto/Expect.fs b/Expecto/Expect.fs
index 0a9088f6..2d19ff2d 100644
--- a/Expecto/Expect.fs
+++ b/Expecto/Expect.fs
@@ -161,6 +161,15 @@ let isNotEmpty (actual : string) format =
   isNotNull actual format
   if String.IsNullOrWhiteSpace actual then Tests.failtestf "%s. Should not be empty." format
 
+/// Expect the passed string is not whitespace
+let isNotWhitespace (actual : string) format =
+  isNotEmpty actual format
+  let rec checkWhitespace index =
+    if Char.IsWhiteSpace actual.[index] then
+      if index < (actual.Length - 1) then checkWhitespace (index + 1)
+      else Tests.failtestf "%s. Should not be whitespace." format
+  checkWhitespace 0
+
 /// Expects the two values to equal each other.
 let inline equal (actual : 'a) (expected : 'a) format =
   match box actual, box expected with