diff --git a/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/ConnectionPoolSizeTest.java b/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/ConnectionPoolSizeTest.java
new file mode 100644
index 0000000000000..bf318df4cb1f6
--- /dev/null
+++ b/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/ConnectionPoolSizeTest.java
@@ -0,0 +1,122 @@
+package io.quarkus.rest.client.reactive;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.net.URI;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import javax.inject.Inject;
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+
+import org.eclipse.microprofile.rest.client.RestClientBuilder;
+import org.jboss.resteasy.reactive.client.api.QuarkusRestClientProperties;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.rest.client.reactive.headers.ClientHeaderParamFromPropertyTest;
+import io.quarkus.test.QuarkusUnitTest;
+import io.quarkus.test.common.http.TestHTTPResource;
+import io.smallrye.mutiny.Uni;
+import io.vertx.core.Vertx;
+
+public class ConnectionPoolSizeTest {
+    @RegisterExtension
+    static final QuarkusUnitTest config = new QuarkusUnitTest()
+            .setArchiveProducer(
+                    () -> ShrinkWrap.create(JavaArchive.class).addClasses(ClientHeaderParamFromPropertyTest.Client.class));
+
+    @TestHTTPResource
+    URI uri;
+
+    @Test
+    void shouldPerform20CallsWithoutQueuing() throws InterruptedException {
+        Client client = RestClientBuilder.newBuilder().baseUri(uri)
+                .build(Client.class);
+
+        CountDownLatch latch = executeCalls(client, 20);
+
+        assertThat(latch.await(2, TimeUnit.SECONDS))
+                .overridingErrorMessage("Failed to do 20 calls in 2 seconds")
+                .isTrue();
+    }
+
+    @Test
+    @Timeout(5)
+    void shouldPerform21CallsWithQueuing() throws InterruptedException {
+        Client client = RestClientBuilder.newBuilder().baseUri(uri)
+                .build(Client.class);
+
+        long start = System.currentTimeMillis();
+        CountDownLatch latch = executeCalls(client, 21);
+        latch.await();
+
+        assertThat(System.currentTimeMillis() - start).isLessThan(3000).isGreaterThanOrEqualTo(2000);
+    }
+
+    @Test
+    @Timeout(5)
+    void shouldPerform5CallsWithoutQueueingOnQueue6() throws InterruptedException {
+        Client client = RestClientBuilder.newBuilder().baseUri(uri)
+                .property(QuarkusRestClientProperties.CONNECTION_POOL_SIZE, 6)
+                .build(Client.class);
+
+        long start = System.currentTimeMillis();
+        CountDownLatch latch = executeCalls(client, 5);
+        latch.await();
+
+        assertThat(System.currentTimeMillis() - start).isLessThan(2000);
+    }
+
+    @Test
+    @Timeout(5)
+    void shouldPerform5CallsWithQueueingOnQueue4() throws InterruptedException {
+        Client client = RestClientBuilder.newBuilder().baseUri(uri)
+                .property(QuarkusRestClientProperties.CONNECTION_POOL_SIZE, 4)
+                .build(Client.class);
+
+        long start = System.currentTimeMillis();
+        CountDownLatch latch = executeCalls(client, 5);
+        latch.await();
+
+        assertThat(System.currentTimeMillis() - start).isLessThan(3000).isGreaterThanOrEqualTo(2000);
+    }
+
+    private CountDownLatch executeCalls(Client client, int callAmount) {
+        ExecutorService executorService = Executors.newFixedThreadPool(callAmount);
+        CountDownLatch latch = new CountDownLatch(callAmount);
+        for (int i = 0; i < callAmount; i++) {
+            executorService.execute(() -> {
+                String result = client.get();
+                latch.countDown();
+                assertThat(result).isEqualTo("hello, world!");
+            });
+        }
+        return latch;
+    }
+
+    @Path("/hello")
+    public interface Client {
+        @GET
+        String get();
+    }
+
+    @Path("/hello")
+    public static class SlowResource {
+        @Inject
+        Vertx vertx;
+
+        @GET
+        public Uni<String> getSlowly() {
+            return Uni.createFrom().emitter(emitter -> vertx.setTimer(1000 /* ms */,
+                    val -> emitter.complete("hello, world!")));
+        }
+    }
+
+}
diff --git a/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/ClientImpl.java b/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/ClientImpl.java
index 8c73b1112f659..728fcc3fc0176 100644
--- a/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/ClientImpl.java
+++ b/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/ClientImpl.java
@@ -70,6 +70,7 @@ public class ClientImpl implements Client {
     private static final Logger log = Logger.getLogger(ClientImpl.class); // TODO: remove
 
     private static final int DEFAULT_CONNECT_TIMEOUT = 15000;
+    private static final int DEFAULT_CONNECTION_POOL_SIZE = 20;
 
     final ClientContext clientContext;
     final boolean closeVertx;
@@ -125,10 +126,13 @@ public Vertx get() {
         }
 
         Object connectionPoolSize = configuration.getProperty(CONNECTION_POOL_SIZE);
-        if (connectionPoolSize != null) {
-            log.infof("Setting connectionPoolSize to %d s", connectionPoolSize);
-            options.setMaxPoolSize((int) connectionPoolSize);
+        if (connectionPoolSize == null) {
+            connectionPoolSize = DEFAULT_CONNECTION_POOL_SIZE;
+        } else {
+            log.debugf("Setting connectionPoolSize to %d s", connectionPoolSize);
         }
+        options.setMaxPoolSize((int) connectionPoolSize);
+
         this.httpClient = this.vertx.createHttpClient(options);
         handlerChain = new HandlerChain(followRedirects);
     }