diff --git a/RestSharp.Tests/StringExtensionsTests.cs b/RestSharp.Tests/StringExtensionsTests.cs
new file mode 100644
index 000000000..7409dfa04
--- /dev/null
+++ b/RestSharp.Tests/StringExtensionsTests.cs
@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using RestSharp.Extensions;
+using Xunit;
+
+namespace RestSharp.Tests
+{
+    public class StringExtensionsTests
+    {
+        [Fact]
+        public void UrlEncode_Throws_ArgumentNullException_For_Null_Input()
+        {
+            const string nullString = null;
+            Assert.Throws<System.ArgumentNullException>(
+                delegate
+                {
+                    nullString.UrlEncode();
+                });   
+        }
+
+        [Fact]
+        public void UrlEncode_Returns_Correct_Length_When_Less_Than_Limit()
+        {
+            const int numLessThanLimit = 32766;
+            string stringWithLimitLength = new string('*', numLessThanLimit);
+            Assert.True(stringWithLimitLength.UrlEncode().Length == numLessThanLimit);
+        }
+
+        [Fact]
+        public void UrlEncode_Returns_Correct_Length_When_More_Than_Limit()
+        {
+            const int numGreaterThanLimit = 65000;
+            string stringWithLimitLength = new string('*', numGreaterThanLimit);
+            Assert.True(stringWithLimitLength.UrlEncode().Length == numGreaterThanLimit);
+        }
+    }
+}
diff --git a/RestSharp/Extensions/StringExtensions.cs b/RestSharp/Extensions/StringExtensions.cs
index fc77d9366..eac4b12f4 100644
--- a/RestSharp/Extensions/StringExtensions.cs
+++ b/RestSharp/Extensions/StringExtensions.cs
@@ -49,7 +49,24 @@ public static string UrlDecode(this string input)
 		/// </summary>
 		public static string UrlEncode(this string input)
 		{
-			return Uri.EscapeDataString(input);
+			const int maxLength = 32766;
+			if (input == null)
+				throw new ArgumentNullException("input");
+
+			if (input.Length <= maxLength)
+				return Uri.EscapeDataString(input);
+
+			StringBuilder sb = new StringBuilder(input.Length * 2);
+			int index = 0;
+			while (index < input.Length)
+			{
+				int length = Math.Min(input.Length - index, maxLength);
+				string subString = input.Substring(index, length);
+				sb.Append(Uri.EscapeDataString(subString));
+				index += subString.Length;
+			}
+
+			return sb.ToString();
 		}
 
 		public static string HtmlDecode(this string input)