diff --git a/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateOrmProcessor.java b/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateOrmProcessor.java
index 4c59cb6647c1b5..51a4d6e6f0307a 100644
--- a/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateOrmProcessor.java
+++ b/extensions/hibernate-orm/deployment/src/main/java/io/quarkus/hibernate/orm/deployment/HibernateOrmProcessor.java
@@ -880,6 +880,17 @@ private void handleHibernateORMWithNoPersistenceXml(
                                 + "To use persistence.xml files, remove all '" + HIBERNATE_ORM_CONFIG_PREFIX
                                 + "*' properties from the Quarkus config file.");
             } else {
+                // It's theoretically possible to use the Quarkus Hibernate ORM extension
+                // without setting any build-time configuration property,
+                // so the condition above might not catch all attempts to use persistence.xml and Quarkus-configured PUs
+                // at the same time.
+                // At that point, the only thing we can do is log something,
+                // so that hopefully people in that situation will notice that their Quarkus configuration is being ignored.
+                LOG.infof(
+                        "A legacy persistence.xml file is present in the classpath. This file will be used to configure JPA/Hibernate ORM persistence units,"
+                                + " and any configuration of the Hibernate ORM extension will be ignored."
+                                + " To ignore persistence.xml files instead, set the configuration property"
+                                + " 'quarkus.hibernate-orm.persistence-xml.ignore' to 'true'.");
                 return;
             }
         }
diff --git a/extensions/hibernate-orm/deployment/src/test/java/io/quarkus/hibernate/orm/xml/persistence/PersistenceXmlTest.java b/extensions/hibernate-orm/deployment/src/test/java/io/quarkus/hibernate/orm/xml/persistence/PersistenceXmlTest.java
index 192432b4f112f9..5439e4bb98e665 100644
--- a/extensions/hibernate-orm/deployment/src/test/java/io/quarkus/hibernate/orm/xml/persistence/PersistenceXmlTest.java
+++ b/extensions/hibernate-orm/deployment/src/test/java/io/quarkus/hibernate/orm/xml/persistence/PersistenceXmlTest.java
@@ -1,11 +1,16 @@
 package io.quarkus.hibernate.orm.xml.persistence;
 
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.hibernate.cfg.AvailableSettings.PERSISTENCE_UNIT_NAME;
 
+import java.util.logging.Formatter;
+import java.util.logging.Level;
+
 import javax.inject.Inject;
 import javax.persistence.EntityManager;
 import javax.transaction.Transactional;
 
+import org.jboss.logmanager.formatters.PatternFormatter;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
@@ -19,8 +24,19 @@
  */
 public class PersistenceXmlTest {
 
+    private static final Formatter LOG_FORMATTER = new PatternFormatter("%s");
     @RegisterExtension
     static QuarkusUnitTest runner = new QuarkusUnitTest()
+            .setLogRecordPredicate(record -> record.getLevel().equals(Level.INFO))
+            .assertLogRecords(records -> assertThat(records)
+                    .as("Logs on startup")
+                    .anySatisfy(record -> {
+                        assertThat(LOG_FORMATTER.formatMessage(record))
+                                .contains("A legacy persistence.xml file is present in the classpath",
+                                        "any configuration of the Hibernate ORM extension will be ignored",
+                                        "To ignore persistence.xml files",
+                                        "set the configuration property 'quarkus.hibernate-orm.persistence-xml.ignore' to 'true'");
+                    }))
             .withApplicationRoot((jar) -> jar
                     .addClass(SmokeTestUtils.class)
                     .addClass(MyEntity.class)