diff --git a/tests/AnthropicClient.Tests/AnthropicClient.Tests.csproj b/tests/AnthropicClient.Tests/AnthropicClient.Tests.csproj
index 491e4db..f21321f 100644
--- a/tests/AnthropicClient.Tests/AnthropicClient.Tests.csproj
+++ b/tests/AnthropicClient.Tests/AnthropicClient.Tests.csproj
@@ -14,6 +14,7 @@
     <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="8.0.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="8.0.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="RichardSzalay.MockHttp" Version="7.0.0" />
     <PackageReference Include="SystemTextJson.JsonDiffPatch.Xunit" Version="2.0.0" />
     <PackageReference Include="xunit" Version="2.5.3" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" />
diff --git a/tests/AnthropicClient.Tests/Integration/AnthropicApiClientTests.cs b/tests/AnthropicClient.Tests/Integration/AnthropicApiClientTests.cs
new file mode 100644
index 0000000..d073564
--- /dev/null
+++ b/tests/AnthropicClient.Tests/Integration/AnthropicApiClientTests.cs
@@ -0,0 +1,34 @@
+namespace AnthropicClient.Tests.Integration;
+
+public class AnthropicApiClientTests : IntegrationTest
+{
+  [Theory]
+  [ClassData(typeof(ErrorTestData))]
+  public async Task CreateChatMessageAsync_WhenCalledAndErrorReturned_ItShouldHandleError(
+    HttpStatusCode statusCode,
+    string content,
+    Type errorType
+  )
+  {
+    _mockHttpMessageHandler
+      .WhenCreateMessageRequest()
+      .Respond(
+        statusCode,
+        "application/json",
+        content
+      );
+
+    var request = new ChatMessageRequest(
+      model: AnthropicModels.Claude3Haiku,
+      messages: [new(MessageRole.User, [new TextContent("Hello!")])]
+    );
+
+    var result = await Client.CreateChatMessageAsync(request);
+
+    result.IsSuccess.Should().BeFalse();
+    result.Error.Should().BeOfType<AnthropicError>();
+    
+    var actualErrorType = result.Error.Error!.GetType();
+    actualErrorType.Should().Be(errorType);
+  }
+}
\ No newline at end of file
diff --git a/tests/AnthropicClient.Tests/Integration/ErrorTestData.cs b/tests/AnthropicClient.Tests/Integration/ErrorTestData.cs
new file mode 100644
index 0000000..ed20c58
--- /dev/null
+++ b/tests/AnthropicClient.Tests/Integration/ErrorTestData.cs
@@ -0,0 +1,100 @@
+namespace AnthropicClient.Tests.Integration;
+
+public class ErrorTestData : IEnumerable<object[]>
+{
+  public IEnumerator<object[]> GetEnumerator()
+  {
+    yield return new object[]
+    {
+      HttpStatusCode.BadRequest,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""invalid_request_error"",
+          ""message"": ""Invalid request.""
+        }
+      }",
+      typeof(InvalidRequestError)
+    };
+
+    yield return new object[]
+    {
+      HttpStatusCode.Unauthorized,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""authentication_error"",
+          ""message"": ""Authentication error.""
+        }
+      }",
+      typeof(AuthenticationError)
+    };
+
+    yield return new object[]
+    {
+      HttpStatusCode.Forbidden,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""permission_error"",
+          ""message"": ""Permission error.""
+        }
+      }",
+      typeof(PermissionError)
+    };
+
+    yield return new object[]
+    {
+      HttpStatusCode.NotFound,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""not_found_error"",
+          ""message"": ""Not found error.""
+        }
+      }",
+      typeof(NotFoundError)
+    };
+
+    yield return new object[]
+    {
+      HttpStatusCode.TooManyRequests,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""rate_limit_error"",
+          ""message"": ""Rate limit error.""
+        }
+      }",
+      typeof(RateLimitError)
+    };
+
+    yield return new object[]
+    {
+      HttpStatusCode.InternalServerError,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""api_error"",
+          ""message"": ""Internal server error.""
+        }
+      }",
+      typeof(ApiError)
+    };
+
+    yield return new object[]
+    {
+      (HttpStatusCode)529,
+      @"{
+        ""type"": ""error"",
+        ""error"": {
+          ""type"": ""overloaded_error"",
+          ""message"": ""Overloaded error.""
+        }
+      }",
+      typeof(OverloadedError)
+    };
+  }
+
+  IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+}
\ No newline at end of file
diff --git a/tests/AnthropicClient.Tests/Integration/IntegrationTest.cs b/tests/AnthropicClient.Tests/Integration/IntegrationTest.cs
new file mode 100644
index 0000000..857fb0f
--- /dev/null
+++ b/tests/AnthropicClient.Tests/Integration/IntegrationTest.cs
@@ -0,0 +1,40 @@
+namespace AnthropicClient.Tests.Integration;
+
+public class IntegrationTest
+{
+  protected readonly MockHttpMessageHandler _mockHttpMessageHandler = new();
+  protected AnthropicApiClient Client => CreateClient();
+
+  private AnthropicApiClient CreateClient()
+  {
+    return new AnthropicApiClient("test-key", _mockHttpMessageHandler.ToHttpClient());
+  }
+}
+
+public static class MockHttpMessageHandlerExtensions
+{
+  private static MockedRequest SetupBaseRequest(this MockHttpMessageHandler mockHttpMessageHandler)
+  {
+    return mockHttpMessageHandler
+      .When(HttpMethod.Post, "https://api.anthropic.com/v1/messages")
+      .WithHeaders(new Dictionary<string, string>
+      {
+        { "anthropic-version", "2023-06-01" },
+        { "x-api-key", "test-key" }
+      });
+  }
+
+  public static MockedRequest WhenCreateMessageRequest(this MockHttpMessageHandler mockHttpMessageHandler)
+  {
+    return mockHttpMessageHandler
+      .SetupBaseRequest()
+      .WithJsonContent<ChatMessageRequest>(r => r.Stream == false);
+  }
+
+  public static MockedRequest WhenCreateStreamMessageRequest(this MockHttpMessageHandler mockHttpMessageHandler)
+  {
+    return mockHttpMessageHandler
+      .SetupBaseRequest()
+      .WithJsonContent<ChatMessageRequest>(r => r.Stream == true);
+  }
+}
\ No newline at end of file
diff --git a/tests/AnthropicClient.Tests/Unit/Utils/JsonSchemaGeneratorTestData.cs b/tests/AnthropicClient.Tests/Unit/Utils/JsonSchemaGeneratorTestData.cs
index 906d68c..b7abfce 100644
--- a/tests/AnthropicClient.Tests/Unit/Utils/JsonSchemaGeneratorTestData.cs
+++ b/tests/AnthropicClient.Tests/Unit/Utils/JsonSchemaGeneratorTestData.cs
@@ -1,4 +1,3 @@
-using System.Collections;
 using System.Text.Json.Nodes;
 
 namespace AnthropicClient.Tests.Unit.Utils;
diff --git a/tests/AnthropicClient.Tests/Usings.cs b/tests/AnthropicClient.Tests/Usings.cs
index 4b78fc5..27ef28a 100644
--- a/tests/AnthropicClient.Tests/Usings.cs
+++ b/tests/AnthropicClient.Tests/Usings.cs
@@ -6,4 +6,8 @@ global using AnthropicClient.Utils;
 
 global using FluentAssertions;
 
-global using Microsoft.Extensions.Configuration;
\ No newline at end of file
+global using Microsoft.Extensions.Configuration;
+
+global using RichardSzalay.MockHttp;
+global using System.Net;
+global using System.Collections;
\ No newline at end of file