diff --git a/hibernate-reactive-core/src/test/java/org/hibernate/reactive/UUIDAsBinaryType.java b/hibernate-reactive-core/src/test/java/org/hibernate/reactive/UUIDAsBinaryType.java
new file mode 100644
index 000000000..2c29500a8
--- /dev/null
+++ b/hibernate-reactive-core/src/test/java/org/hibernate/reactive/UUIDAsBinaryType.java
@@ -0,0 +1,176 @@
+/* Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright: Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.reactive;
+
+import java.util.Objects;
+import java.util.UUID;
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+import org.hibernate.cfg.Configuration;
+import org.hibernate.reactive.mutiny.Mutiny;
+import org.hibernate.reactive.testing.DatabaseSelectionRule;
+
+import org.junit.Rule;
+import org.junit.Test;
+
+import io.vertx.ext.unit.TestContext;
+
+import static java.util.Arrays.asList;
+import static org.hibernate.reactive.containers.DatabaseConfiguration.DBType.MARIA;
+import static org.hibernate.reactive.containers.DatabaseConfiguration.DBType.MYSQL;
+import static org.hibernate.reactive.testing.DatabaseSelectionRule.runOnlyFor;
+import static org.hibernate.reactive.testing.DatabaseSelectionRule.skipTestsFor;
+
+public abstract class UUIDAsBinaryType extends BaseReactiveTest {
+
+	public static class ForMySQLandMariaDBTest extends UUIDAsBinaryType {
+		// There's an issue querying for Binary types if the size of the column is different from
+		// the size of the parameter: see https://github.com/hibernate/hibernate-reactive/issues/678
+		@Rule
+		public DatabaseSelectionRule rule = runOnlyFor( MYSQL, MARIA );
+
+		@Override
+		protected Configuration constructConfiguration() {
+			Configuration configuration = super.constructConfiguration();
+			configuration.addAnnotatedClass( ExactSizeUUIDEntity.class );
+			return configuration;
+		}
+
+		@Test
+		public void exactSize(TestContext context) {
+			ExactSizeUUIDEntity entityA = new ExactSizeUUIDEntity( "Exact Size A" );
+			ExactSizeUUIDEntity entityB = new ExactSizeUUIDEntity( "Exact Size B" );
+
+			Mutiny.Session session = openMutinySession();
+			test( context, session
+					.persistAll( entityA, entityB )
+					.call( session::flush )
+					.invoke( () -> context.assertNotEquals( entityA.id, entityB.id ) )
+					.chain( () -> openMutinySession().find( ExactSizeUUIDEntity.class, entityA.id, entityB.id ) )
+					.invoke( list -> {
+						context.assertEquals( list.size(), 2 );
+						context.assertTrue( list.containsAll( asList( entityA, entityB ) ) );
+					} )
+			);
+		}
+
+		@Entity
+		private static class ExactSizeUUIDEntity {
+
+			@Id
+			@GeneratedValue
+			@Column(columnDefinition = "binary(16)")
+			UUID id;
+
+			@Column(unique = true)
+			String name;
+
+			public ExactSizeUUIDEntity() {
+			}
+
+			public ExactSizeUUIDEntity(String name) {
+				this.name = name;
+			}
+
+			@Override
+			public boolean equals(Object o) {
+				if ( this == o ) {
+					return true;
+				}
+				if ( o == null || getClass() != o.getClass() ) {
+					return false;
+				}
+				ExactSizeUUIDEntity that = (ExactSizeUUIDEntity) o;
+				return Objects.equals( name, that.name );
+			}
+
+			@Override
+			public int hashCode() {
+				return Objects.hash( name );
+			}
+
+			@Override
+			public String toString() {
+				return id + ":" + name;
+			}
+		}
+
+	}
+
+	public static class ForOtherDbsTest extends UUIDAsBinaryType {
+
+		@Rule
+		public DatabaseSelectionRule rule = skipTestsFor( MYSQL, MARIA );
+
+		@Override
+		protected Configuration constructConfiguration() {
+			Configuration configuration = super.constructConfiguration();
+			configuration.addAnnotatedClass( UUIDEntity.class );
+			return configuration;
+		}
+
+		@Test
+		public void uuidIdentifierWithMutinyAPI(TestContext context) {
+			UUIDEntity entityA = new UUIDEntity( "UUID A" );
+			UUIDEntity entityB = new UUIDEntity( "UUID B" );
+
+			Mutiny.Session session = openMutinySession();
+			test( context, session
+					.persistAll( entityA, entityB )
+					.call( session::flush )
+					.invoke( () -> context.assertNotEquals( entityA.id, entityB.id ) )
+					.chain( () -> openMutinySession().find( UUIDEntity.class, entityA.id, entityB.id ) )
+					.invoke( list -> {
+						context.assertEquals( list.size(), 2 );
+						context.assertTrue( list.containsAll( asList( entityA, entityB ) ) );
+					} )
+			);
+		}
+
+		@Entity
+		private static class UUIDEntity {
+
+			@Id
+			@GeneratedValue
+			UUID id;
+
+			@Column(unique = true)
+			String name;
+
+			public UUIDEntity() {
+			}
+
+			public UUIDEntity(String name) {
+				this.name = name;
+			}
+
+			@Override
+			public boolean equals(Object o) {
+				if ( this == o ) {
+					return true;
+				}
+				if ( o == null || getClass() != o.getClass() ) {
+					return false;
+				}
+				UUIDEntity that = (UUIDEntity) o;
+				return Objects.equals( name, that.name );
+			}
+
+			@Override
+			public int hashCode() {
+				return Objects.hash( name );
+			}
+
+			@Override
+			public String toString() {
+				return id + ":" + name;
+			}
+		}
+	}
+}