diff --git a/scripts/run_integration_tests.sh b/scripts/run_integration_tests.sh
index c8aa7b5..2a219c5 100755
--- a/scripts/run_integration_tests.sh
+++ b/scripts/run_integration_tests.sh
@@ -29,5 +29,6 @@ fi
 
 # Run serially to reduce the chance of hitting rate limits.
 cargo test --all-features --test integration_tests -- "${ARGS[@]}"
+cargo test --all-features --test ws_integration_tests -- "${ARGS[@]}"
 cargo test --all-features --test simple_auth_test -- "${ARGS[@]}"
 cargo test --all-features --test order_posting_test -- "${ARGS[@]}"
diff --git a/tests/ws_integration_tests.rs b/tests/ws_integration_tests.rs
new file mode 100644
index 0000000..a609eb3
--- /dev/null
+++ b/tests/ws_integration_tests.rs
@@ -0,0 +1,64 @@
+// WebSocket integration tests for polyfill-rs
+//
+// These tests connect to Polymarket's live WS endpoints and are ignored by default.
+//
+// Run with:
+//   cargo test --all-features --test ws_integration_tests -- --ignored --nocapture --test-threads=1
+
+#![cfg(feature = "stream")]
+
+use futures::StreamExt;
+use polyfill_rs::{ClobClient, OrderBookManager, WebSocketStream, WsBookUpdateProcessor};
+use std::time::Duration;
+
+const HOST: &str = "https://clob.polymarket.com";
+const WS_MARKET_URL: &str = "wss://ws-subscriptions-clob.polymarket.com/ws/market";
+
+#[tokio::test(flavor = "multi_thread")]
+#[ignore]
+async fn test_real_ws_market_book_applier_receives_book_update() {
+    // Pick an active token ID so the market channel should produce data.
+    let client = ClobClient::new(HOST);
+    let markets = client
+        .get_sampling_markets(None)
+        .await
+        .expect("failed to fetch markets");
+
+    let token_id = markets
+        .data
+        .iter()
+        .find(|m| m.active && !m.closed)
+        .and_then(|m| m.tokens.first())
+        .map(|t| t.token_id.clone())
+        .expect("no active markets found");
+
+    let books = OrderBookManager::new(256);
+    books
+        .get_or_create_book(&token_id)
+        .expect("failed to create book");
+
+    let mut ws = WebSocketStream::new(WS_MARKET_URL);
+    ws.subscribe_market_channel(vec![token_id.clone()])
+        .await
+        .expect("failed to subscribe market channel");
+
+    let processor = WsBookUpdateProcessor::new(256 * 1024);
+    let mut applier = ws.into_book_applier(&books, processor);
+
+    let stats = tokio::time::timeout(Duration::from_secs(10), applier.next())
+        .await
+        .expect("timed out waiting for WS book message")
+        .expect("WS stream ended unexpectedly")
+        .expect("WS processing error");
+
+    assert!(
+        stats.book_messages > 0,
+        "expected at least one book message"
+    );
+
+    let snapshot = books.get_book(&token_id).expect("failed to read book");
+    assert!(
+        !snapshot.bids.is_empty() || !snapshot.asks.is_empty(),
+        "expected some book levels after applying an update"
+    );
+}