diff --git a/vllm/benchmarks/lib/endpoint_request_func.py b/vllm/benchmarks/lib/endpoint_request_func.py
index ee6ea65633..f426e78c74 100644
--- a/vllm/benchmarks/lib/endpoint_request_func.py
+++ b/vllm/benchmarks/lib/endpoint_request_func.py
@@ -376,13 +376,13 @@ async def async_request_openai_chat_completions(
     output.prompt_len = request_func_input.prompt_len
 
     generated_text = ""
-    ttft = 0.0
     st = time.perf_counter()
     output.start_time = st
     most_recent_timestamp = st
     try:
         async with session.post(url=api_url, json=payload, headers=headers) as response:
             if response.status == 200:
+                first_chunk_received = False
                 handler = StreamedResponseHandler()
                 async for chunk_bytes in response.content.iter_any():
                     chunk_bytes = chunk_bytes.strip()
@@ -406,9 +406,9 @@ async def async_request_openai_chat_completions(
                             if choices := data.get("choices"):
                                 content = choices[0]["delta"].get("content")
                                 # First token
-                                if ttft == 0.0:
-                                    ttft = timestamp - st
-                                    output.ttft = ttft
+                                if not first_chunk_received:
+                                    first_chunk_received = True
+                                    output.ttft = timestamp - st
 
                                 # Decoding phase
                                 else:
@@ -423,7 +423,14 @@ async def async_request_openai_chat_completions(
                             most_recent_timestamp = timestamp
 
                 output.generated_text = generated_text
-                output.success = True
+                if first_chunk_received:
+                    output.success = True
+                else:
+                    output.success = False
+                    output.error = (
+                        "Never received a valid chunk to calculate TTFT."
+                        "This response will be marked as failed!"
+                    )
                 output.latency = most_recent_timestamp - st
             else:
                 output.error = response.reason or ""
@@ -494,7 +501,6 @@ async def async_request_openai_audio(
         output.input_audio_duration = input_audio_duration
 
         generated_text = ""
-        ttft = 0.0
         st = time.perf_counter()
         output.start_time = st
         most_recent_timestamp = st
@@ -503,6 +509,7 @@ async def async_request_openai_audio(
                 url=api_url, data=form, headers=headers
             ) as response:
                 if response.status == 200:
+                    first_chunk_received = False
                     handler = StreamedResponseHandler()
 
                     async for chunk_bytes in response.content.iter_any():
@@ -522,9 +529,9 @@ async def async_request_openai_audio(
                                 if choices := data.get("choices"):
                                     content = choices[0]["delta"].get("content")
                                     # First token
-                                    if ttft == 0.0:
-                                        ttft = timestamp - st
-                                        output.ttft = ttft
+                                    if not first_chunk_received:
+                                        first_chunk_received = True
+                                        output.ttft = timestamp - st
 
                                     # Decoding phase
                                     else:
@@ -541,7 +548,14 @@ async def async_request_openai_audio(
                                 most_recent_timestamp = timestamp
 
                     output.generated_text = generated_text
-                    output.success = True
+                    if first_chunk_received:
+                        output.success = True
+                    else:
+                        output.success = False
+                        output.error = (
+                            "Never received a valid chunk to calculate TTFT."
+                            "This response will be marked as failed!"
+                        )
                     output.latency = most_recent_timestamp - st
                 else:
                     output.error = response.reason or ""