diff --git a/dotnet/tests/AzureAIAgentsPersistent.IntegrationTests/AzureAIAgentsPersistentCreateTests.cs b/dotnet/tests/AzureAIAgentsPersistent.IntegrationTests/AzureAIAgentsPersistentCreateTests.cs
index 17fad1581f..a10cc11d79 100644
--- a/dotnet/tests/AzureAIAgentsPersistent.IntegrationTests/AzureAIAgentsPersistentCreateTests.cs
+++ b/dotnet/tests/AzureAIAgentsPersistent.IntegrationTests/AzureAIAgentsPersistentCreateTests.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Threading.Tasks;
 using AgentConformance.IntegrationTests.Support;
@@ -108,6 +109,9 @@ You are a helpful agent that can help fetch data from files you know about.
         );
         var vectorStoreMetadata = await this._persistentAgentsClient.VectorStores.CreateVectorStoreAsync([uploadedAgentFile.Id], name: "WordCodeLookup_VectorStore");
 
+        // Wait for vector store indexing to complete before using it
+        await this.WaitForVectorStoreReadyAsync(this._persistentAgentsClient, vectorStoreMetadata.Value.Id);
+
         // Act.
         var agent = createMechanism switch
         {
@@ -292,4 +296,42 @@ public async Task CreateAgent_CreatesAgentWithAIFunctionToolsAsync(string create
             await this._persistentAgentsClient.Administration.DeleteAgentAsync(agent.Id);
         }
     }
+
+    /// <summary>
+    /// Waits for a vector store to complete indexing by polling its status.
+    /// </summary>
+    /// <param name="client">The persistent agents client.</param>
+    /// <param name="vectorStoreId">The ID of the vector store.</param>
+    /// <param name="maxWaitSeconds">Maximum time to wait in seconds (default: 30).</param>
+    /// <returns>A task that completes when the vector store is ready or throws on timeout/failure.</returns>
+    private async Task WaitForVectorStoreReadyAsync(
+        PersistentAgentsClient client,
+        string vectorStoreId,
+        int maxWaitSeconds = 30)
+    {
+        Stopwatch sw = Stopwatch.StartNew();
+        while (sw.Elapsed.TotalSeconds < maxWaitSeconds)
+        {
+            PersistentAgentsVectorStore vectorStore = await client.VectorStores.GetVectorStoreAsync(vectorStoreId);
+
+            if (vectorStore.Status == VectorStoreStatus.Completed)
+            {
+                if (vectorStore.FileCounts.Failed > 0)
+                {
+                    throw new InvalidOperationException("Vector store indexing failed for some files");
+                }
+
+                return;
+            }
+
+            if (vectorStore.Status == VectorStoreStatus.Expired)
+            {
+                throw new InvalidOperationException("Vector store has expired");
+            }
+
+            await Task.Delay(1000);
+        }
+
+        throw new TimeoutException($"Vector store did not complete indexing within {maxWaitSeconds}s");
+    }
 }
diff --git a/dotnet/tests/OpenAIAssistant.IntegrationTests/OpenAIAssistantClientExtensionsTests.cs b/dotnet/tests/OpenAIAssistant.IntegrationTests/OpenAIAssistantClientExtensionsTests.cs
index d187d85b78..f1373bd98b 100644
--- a/dotnet/tests/OpenAIAssistant.IntegrationTests/OpenAIAssistantClientExtensionsTests.cs
+++ b/dotnet/tests/OpenAIAssistant.IntegrationTests/OpenAIAssistantClientExtensionsTests.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Threading.Tasks;
 using AgentConformance.IntegrationTests.Support;
@@ -173,6 +174,9 @@ You are a helpful agent that can help fetch data from files you know about.
         });
         string vectorStoreId = vectorStoreCreate.Value.Id;
 
+        // Wait for vector store indexing to complete before using it
+        await WaitForVectorStoreReadyAsync(vectorStoreClient, vectorStoreId);
+
         var fileSearchTool = new HostedFileSearchTool() { Inputs = [new HostedVectorStoreContent(vectorStoreId)] };
 
         var agent = createMechanism switch
@@ -219,4 +223,43 @@ You are a helpful agent that can help fetch data from files you know about.
             File.Delete(searchFilePath);
         }
     }
+
+    /// <summary>
+    /// Waits for a vector store to complete indexing by polling its status.
+    /// </summary>
+    /// <param name="client">The vector store client.</param>
+    /// <param name="vectorStoreId">The ID of the vector store.</param>
+    /// <param name="maxWaitSeconds">Maximum time to wait in seconds (default: 30).</param>
+    /// <returns>A task that completes when the vector store is ready or throws on timeout/failure.</returns>
+    private static async Task WaitForVectorStoreReadyAsync(
+        VectorStoreClient client,
+        string vectorStoreId,
+        int maxWaitSeconds = 30)
+    {
+        Stopwatch sw = Stopwatch.StartNew();
+        while (sw.Elapsed.TotalSeconds < maxWaitSeconds)
+        {
+            VectorStore vectorStore = await client.GetVectorStoreAsync(vectorStoreId);
+            VectorStoreStatus status = vectorStore.Status;
+
+            if (status == VectorStoreStatus.Completed)
+            {
+                if (vectorStore.FileCounts.Failed > 0)
+                {
+                    throw new InvalidOperationException("Vector store indexing failed for some files");
+                }
+
+                return;
+            }
+
+            if (status == VectorStoreStatus.Expired)
+            {
+                throw new InvalidOperationException("Vector store has expired");
+            }
+
+            await Task.Delay(1000);
+        }
+
+        throw new TimeoutException($"Vector store did not complete indexing within {maxWaitSeconds}s");
+    }
 }