diff --git a/index.js b/index.js
index 04d8371..88beaf8 100644
--- a/index.js
+++ b/index.js
@@ -236,6 +236,19 @@
     return this;
   };
 
+  /**
+   * Checks if the string equals another case insensitively.
+   */
+
+  Assertion.prototype.equalCaseInsensitive = function (obj) {
+    this.assert(
+        expect.equalCaseInsensitive(this.obj, obj)
+        , function(){ return 'expected ' + i(this.obj) + ' to be equal case insensitively ' + i(obj) }
+        , function(){ return 'expected ' + i(this.obj) + ' to be not equal case insensitively ' + i(obj) }
+        , obj);
+    return this;
+  };
+
   /**
    * Assert within start to finish (inclusive).
    *
@@ -910,6 +923,26 @@
     }
   };
 
+  /**
+   * Asserts strings equality case-insensitive
+   */
+
+  expect.equalCaseInsensitive = function equalCaseInsensitive(actual, expected) {
+    // check if values are string
+    if (typeof actual != "string" && typeof expected != "string"){
+      throw new Error(`values are not string, actual value is a ${typeof actual} and expected value is a ${typeof expected}`);
+    } else if (typeof actual != "string"){
+      throw new Error(`actual value is not string, it's a ${typeof actual}`);
+    } else if (typeof expected != "string"){
+      throw new Error(`expected value is not string, it's a ${typeof expected}`);
+    }
+
+    // check values equality case-insensitive
+    const lowerCaseActual = actual.toLowerCase();
+    const lowerCaseExpected = expected.toLowerCase();
+    return lowerCaseActual === lowerCaseExpected;
+  };
+
   function isUndefinedOrNull (value) {
     return value === null || value === undefined;
   }