diff --git a/OpenAI_API/APIAuthentication.cs b/OpenAI_API/APIAuthentication.cs
index 1c1ff36..4346281 100644
--- a/OpenAI_API/APIAuthentication.cs
+++ b/OpenAI_API/APIAuthentication.cs
@@ -1,5 +1,8 @@
 using System;
+using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
+using System.Threading.Tasks;
 
 namespace OpenAI_API
 {
@@ -156,6 +159,32 @@ public static APIAuthentication LoadFromPath(string directory = null, string fil
 		}
 
 
+		/// <summary>
+		/// Tests the api key against the OpenAI API, to ensure it is valid.  This hits the models endpoint so should not be charged for usage.
+		/// </summary>
+		/// <returns><see langword="true"/> if the api key is valid, or <see langword="false"/> if empty or not accepted by the OpenAI API.</returns>
+		public async Task<bool> ValidateAPIKey()
+		{
+			if (string.IsNullOrEmpty(ApiKey))
+				return false;
+
+			var api = new OpenAIAPI(this);
+
+			List<Models.Model> results;
+
+			try
+			{
+				results = await api.Models.GetModelsAsync();
+			}
+			catch (Exception ex)
+			{
+				Debug.WriteLine(ex.ToString());
+				return false;
+			}
+
+			return (results.Count > 0);
+		}
+
 	}
 
 	internal static class AuthHelpers
diff --git a/OpenAI_API/EndpointBase.cs b/OpenAI_API/EndpointBase.cs
index b25336c..2734e96 100644
--- a/OpenAI_API/EndpointBase.cs
+++ b/OpenAI_API/EndpointBase.cs
@@ -135,7 +135,18 @@ private async Task<HttpResponseMessage> HttpRequestRaw(string url = null, HttpMe
 					resultAsString = "Additionally, the following error was thrown when attemping to read the response content: " + e.ToString();
 				}
 
-				throw new HttpRequestException(GetErrorMessage(resultAsString, response, Endpoint, url));
+				if (response.StatusCode == System.Net.HttpStatusCode.Unauthorized)
+				{
+					throw new AuthenticationException("OpenAI rejected your authorization, most likely due to an invalid API Key.  Try checking your API Key and see https://github.com/OkGoDoIt/OpenAI-API-dotnet#authentication for guidance.  Full API response follows: " + resultAsString);
+				}
+				else if (response.StatusCode == System.Net.HttpStatusCode.InternalServerError)
+				{
+					throw new HttpRequestException("OpenAI had an internal server error, which can happen occasionally.  Please retry your request.  " + GetErrorMessage(resultAsString, response, Endpoint, url));
+				}
+				else
+				{
+					throw new HttpRequestException(GetErrorMessage(resultAsString, response, Endpoint, url));
+				}
 			}
 		}
 
diff --git a/OpenAI_Tests/AuthTests.cs b/OpenAI_Tests/AuthTests.cs
index 5d4b43f..e791c81 100644
--- a/OpenAI_Tests/AuthTests.cs
+++ b/OpenAI_Tests/AuthTests.cs
@@ -1,6 +1,7 @@
 using NUnit.Framework;
 using System;
 using System.IO;
+using System.Threading.Tasks;
 
 namespace OpenAI_Tests
 {
@@ -105,5 +106,22 @@ public void ParseKey()
 			Assert.AreEqual("orgTest", auth.OpenAIOrganization);
 		}
 
+		[Test]
+		public async Task TestBadKey()
+		{
+			var auth = new OpenAI_API.APIAuthentication("pk-testAA");
+			Assert.IsFalse(await auth.ValidateAPIKey());
+
+			auth = new OpenAI_API.APIAuthentication(null);
+			Assert.IsFalse(await auth.ValidateAPIKey());
+		}
+
+		[Test]
+		public async Task TestValidateGoodKey()
+		{
+			var auth = new OpenAI_API.APIAuthentication(Environment.GetEnvironmentVariable("TEST_OPENAI_SECRET_KEY"));
+			Assert.IsTrue(await auth.ValidateAPIKey());
+		}
+
 	}
 }
\ No newline at end of file
diff --git a/OpenAI_Tests/CompletionEndpointTests.cs b/OpenAI_Tests/CompletionEndpointTests.cs
index b65b292..936cecb 100644
--- a/OpenAI_Tests/CompletionEndpointTests.cs
+++ b/OpenAI_Tests/CompletionEndpointTests.cs
@@ -1,5 +1,4 @@
 using NUnit.Framework;
-using OpenAI_API;
 using System;
 using System.Linq;
 using System.Threading.Tasks;
diff --git a/OpenAI_Tests/EmbeddingEndpointTests.cs b/OpenAI_Tests/EmbeddingEndpointTests.cs
index 570a504..ee58a57 100644
--- a/OpenAI_Tests/EmbeddingEndpointTests.cs
+++ b/OpenAI_Tests/EmbeddingEndpointTests.cs
@@ -1,5 +1,4 @@
 using NUnit.Framework;
-using OpenAI_API;
 using OpenAI_API.Embedding;
 using OpenAI_API.Models;
 using System;
diff --git a/OpenAI_Tests/ModelEndpointTests.cs b/OpenAI_Tests/ModelEndpointTests.cs
index f197631..3ccfef6 100644
--- a/OpenAI_Tests/ModelEndpointTests.cs
+++ b/OpenAI_Tests/ModelEndpointTests.cs
@@ -4,7 +4,7 @@
 using OpenAI_API.Models;
 using System;
 using System.Linq;
-using System.Net.Http;
+using System.Security.Authentication;
 using System.Threading.Tasks;
 
 namespace OpenAI_Tests
@@ -66,7 +66,7 @@ public void GetEnginesAsync_ShouldFailIfInvalidAuthIsProvided()
 			var api = new OpenAIAPI(new APIAuthentication(Guid.NewGuid().ToString()));
 			Func<Task> act = () => api.Models.GetModelsAsync();
 			act.Should()
-				.ThrowAsync<HttpRequestException>()
+				.ThrowAsync<AuthenticationException>()
 				.Where(exc => exc.Message.Contains("Incorrect API key provided"));
 		}