diff --git a/libs/langchain-azure-openai/src/chat_models.ts b/libs/langchain-azure-openai/src/chat_models.ts
index 6acda2300b23..ffa7c8030adb 100644
--- a/libs/langchain-azure-openai/src/chat_models.ts
+++ b/libs/langchain-azure-openai/src/chat_models.ts
@@ -266,15 +266,27 @@ export class AzureChatOpenAI
       (getEnvironmentVariable("AZURE_OPENAI_API_KEY") ||
         getEnvironmentVariable("OPENAI_API_KEY"));
 
+    const azureCredential =
+      fields?.credentials ??
+      (fields?.azureOpenAIApiKey ||
+      getEnvironmentVariable("AZURE_OPENAI_API_KEY")
+        ? new AzureKeyCredential(this.azureOpenAIApiKey ?? "")
+        : new OpenAIKeyCredential(this.azureOpenAIApiKey ?? ""));
+
+    const isOpenAIApiKey =
+      fields?.azureOpenAIApiKey ||
+      // eslint-disable-next-line no-instanceof/no-instanceof
+      azureCredential instanceof OpenAIKeyCredential;
+
     if (!this.azureOpenAIApiKey && !fields?.credentials) {
       throw new Error("Azure OpenAI API key not found");
     }
 
-    if (!this.azureOpenAIEndpoint) {
+    if (!this.azureOpenAIEndpoint && !isOpenAIApiKey) {
       throw new Error("Azure OpenAI Endpoint not found");
     }
 
-    if (!this.azureOpenAIApiDeploymentName) {
+    if (!this.azureOpenAIApiDeploymentName && !isOpenAIApiKey) {
       throw new Error("Azure OpenAI Deployment name not found");
     }
 
@@ -294,28 +306,25 @@ export class AzureChatOpenAI
 
     this.streaming = fields?.streaming ?? false;
 
-    const azureCredential =
-      fields?.credentials ??
-      (fields?.azureOpenAIApiKey ||
-      getEnvironmentVariable("AZURE_OPENAI_API_KEY")
-        ? new AzureKeyCredential(this.azureOpenAIApiKey ?? "")
-        : new OpenAIKeyCredential(this.azureOpenAIApiKey ?? ""));
+    const options = {
+      userAgentOptions: { userAgentPrefix: USER_AGENT_PREFIX },
+    };
 
-    if (isTokenCredential(azureCredential)) {
+    if (isOpenAIApiKey) {
+      this.client = new AzureOpenAIClient(
+        azureCredential as OpenAIKeyCredential
+      );
+    } else if (isTokenCredential(azureCredential)) {
       this.client = new AzureOpenAIClient(
         this.azureOpenAIEndpoint ?? "",
         azureCredential as TokenCredential,
-        {
-          userAgentOptions: { userAgentPrefix: USER_AGENT_PREFIX },
-        }
+        options
       );
     } else {
       this.client = new AzureOpenAIClient(
         this.azureOpenAIEndpoint ?? "",
         azureCredential as KeyCredential,
-        {
-          userAgentOptions: { userAgentPrefix: USER_AGENT_PREFIX },
-        }
+        options
       );
     }
   }
@@ -339,11 +348,11 @@ export class AzureChatOpenAI
     options: this["ParsedCallOptions"]
   ): Promise<EventStream<ChatCompletions>> {
     return this.caller.call(async () => {
-      if (!this.azureOpenAIApiDeploymentName) {
-        throw new Error("Azure OpenAI Deployment name not found");
-      }
+      const deploymentName =
+        this.azureOpenAIApiDeploymentName || this.modelName;
+
       const res = await this.client.streamChatCompletions(
-        this.azureOpenAIApiDeploymentName,
+        deploymentName,
         azureOpenAIMessages,
         {
           functions: options?.functions,
@@ -434,10 +443,7 @@ export class AzureChatOpenAI
     options: this["ParsedCallOptions"],
     runManager?: CallbackManagerForLLMRun
   ): Promise<ChatResult> {
-    if (!this.azureOpenAIApiDeploymentName) {
-      throw new Error("Azure OpenAI Deployment name not found");
-    }
-    const deploymentName = this.azureOpenAIApiDeploymentName;
+    const deploymentName = this.azureOpenAIApiDeploymentName || this.modelName;
     const tokenUsage: TokenUsage = {};
     const azureOpenAIMessages: ChatRequestMessage[] =
       this.formatMessages(messages);
diff --git a/libs/langchain-azure-openai/src/tests/chat_models.int.test.ts b/libs/langchain-azure-openai/src/tests/chat_models.int.test.ts
index 2a4d7e01d717..e5c48c1e13fc 100644
--- a/libs/langchain-azure-openai/src/tests/chat_models.int.test.ts
+++ b/libs/langchain-azure-openai/src/tests/chat_models.int.test.ts
@@ -16,6 +16,8 @@ import {
 import { CallbackManager } from "@langchain/core/callbacks/manager";
 import { NewTokenIndices } from "@langchain/core/callbacks/base";
 import { InMemoryCache } from "@langchain/core/caches";
+import { getEnvironmentVariable } from "@langchain/core/utils/env";
+import { OpenAIKeyCredential } from "@azure/openai";
 import { AzureChatOpenAI } from "../chat_models.js";
 
 test("Test ChatOpenAI", async () => {
@@ -790,3 +792,19 @@ test("Test ChatOpenAI token usage reporting for streaming calls", async () => {
     expect(streamingTokenUsed).toEqual(nonStreamingTokenUsed);
   }
 });
+
+test("Test ChatOpenAI with OpenAI API key credentials", async () => {
+  const openAiKey: string = getEnvironmentVariable("OPENAI_API_KEY") ?? "";
+  const credentials = new OpenAIKeyCredential(openAiKey);
+
+  const chat = new AzureChatOpenAI({
+    modelName: "gpt-3.5-turbo",
+    maxTokens: 5,
+    credentials,
+    azureOpenAIEndpoint: "",
+    azureOpenAIApiDeploymentName: "",
+  });
+  const message = new HumanMessage("Hello!");
+  const res = await chat.invoke([["system", "Say hi"], message]);
+  console.log(res);
+});