diff --git a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/MongoProperties.java b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/MongoProperties.java
index 3f1e5c1793..aaf274f8e0 100644
--- a/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/MongoProperties.java
+++ b/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mongo/MongoProperties.java
@@ -35,13 +35,16 @@ import com.mongodb.ServerAddress;
  * @author Dave Syer
  * @author Phillip Webb
  * @author Josh Long
+ * @author Andy Wilkinson
  */
 @ConfigurationProperties(prefix = "spring.data.mongodb")
 public class MongoProperties {
 
+	private static final int DEFAULT_PORT = 27017;
+
 	private String host;
 
-	private int port = 27017;
+	private Integer port = null;
 
 	private String uri = "mongodb://localhost/test";
 
@@ -112,11 +115,11 @@ public class MongoProperties {
 		this.uri = uri;
 	}
 
-	public int getPort() {
+	public Integer getPort() {
 		return this.port;
 	}
 
-	public void setPort(int port) {
+	public void setPort(Integer port) {
 		this.port = port;
 	}
 
@@ -138,17 +141,19 @@ public class MongoProperties {
 	public MongoClient createMongoClient(MongoClientOptions options)
 			throws UnknownHostException {
 		try {
-			if (this.host != null) {
+			if (customAddress() || customCredentials()) {
 				if (options == null) {
 					options = MongoClientOptions.builder().build();
 				}
 				List<MongoCredential> credentials = null;
-				if (this.password != null && this.username != null) {
+				if (customCredentials()) {
 					credentials = Arrays.asList(MongoCredential.createMongoCRCredential(
 							this.username, getMongoClientDatabase(), this.password));
 				}
-				return new MongoClient(Arrays.asList(new ServerAddress(this.host,
-						this.port)), credentials, options);
+				String host = this.host == null ? "localhost" : this.host;
+				int port = this.port == null ? DEFAULT_PORT : this.port;
+				return new MongoClient(Arrays.asList(new ServerAddress(host, port)),
+						credentials, options);
 			}
 			// The options and credentials are in the URI
 			return new MongoClient(new MongoClientURI(this.uri, builder(options)));
@@ -158,6 +163,14 @@ public class MongoProperties {
 		}
 	}
 
+	private boolean customAddress() {
+		return this.host != null || this.port != null;
+	}
+
+	private boolean customCredentials() {
+		return this.username != null && this.password != null;
+	}
+
 	private Builder builder(MongoClientOptions options) {
 		Builder builder = MongoClientOptions.builder();
 		if (options != null) {
diff --git a/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mongo/MongoPropertiesTests.java b/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mongo/MongoPropertiesTests.java
index 60105a2a52..986b0d2db9 100644
--- a/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mongo/MongoPropertiesTests.java
+++ b/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/mongo/MongoPropertiesTests.java
@@ -16,19 +16,29 @@
 
 package org.springframework.boot.autoconfigure.mongo;
 
+import java.net.UnknownHostException;
+import java.util.List;
+
 import org.junit.Test;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Configuration;
 
+import com.mongodb.MongoClient;
+import com.mongodb.MongoCredential;
+import com.mongodb.ServerAddress;
+
 import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.hasSize;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertThat;
 
 /**
  * Tests for {@link MongoProperties}.
  *
  * @author Phillip Webb
+ * @author Andy Wilkinson
  */
 public class MongoPropertiesTests {
 
@@ -43,6 +53,66 @@ public class MongoPropertiesTests {
 		assertThat(properties.getPassword(), equalTo("word".toCharArray()));
 	}
 
+	@Test
+	public void portCanBeCustomized() throws UnknownHostException {
+		MongoProperties properties = new MongoProperties();
+		properties.setPort(12345);
+		MongoClient client = properties.createMongoClient(null);
+		List<ServerAddress> allAddresses = client.getAllAddress();
+		assertThat(allAddresses, hasSize(1));
+		assertServerAddress(allAddresses.get(0), "localhost", 12345);
+	}
+
+	@Test
+	public void hostCanBeCustomized() throws UnknownHostException {
+		MongoProperties properties = new MongoProperties();
+		properties.setHost("mongo.example.com");
+		MongoClient client = properties.createMongoClient(null);
+		List<ServerAddress> allAddresses = client.getAllAddress();
+		assertThat(allAddresses, hasSize(1));
+		assertServerAddress(allAddresses.get(0), "mongo.example.com", 27017);
+	}
+
+	@Test
+	public void credentialsCanBeCustomized() throws UnknownHostException {
+		MongoProperties properties = new MongoProperties();
+		properties.setUsername("user");
+		properties.setPassword("secret".toCharArray());
+
+		MongoClient client = properties.createMongoClient(null);
+
+		assertMongoCredential(client.getCredentialsList().get(0), "user", "secret");
+	}
+
+	@Test
+	public void uriCanBeCustomized() throws UnknownHostException {
+		MongoProperties properties = new MongoProperties();
+		properties
+				.setUri("mongodb://user:secret@mongo1.example.com:12345,mongo2.example.com:23456/test");
+		MongoClient client = properties.createMongoClient(null);
+
+		List<ServerAddress> allAddresses = client.getAllAddress();
+		assertEquals(2, allAddresses.size());
+		assertServerAddress(allAddresses.get(0), "mongo1.example.com", 12345);
+		assertServerAddress(allAddresses.get(1), "mongo2.example.com", 23456);
+
+		List<MongoCredential> credentialsList = client.getCredentialsList();
+		assertEquals(1, credentialsList.size());
+		assertMongoCredential(credentialsList.get(0), "user", "secret");
+	}
+
+	private void assertServerAddress(ServerAddress serverAddress, String expectedHost,
+			int expectedPort) {
+		assertThat(serverAddress.getHost(), equalTo(expectedHost));
+		assertThat(serverAddress.getPort(), equalTo(expectedPort));
+	}
+
+	private void assertMongoCredential(MongoCredential credentials,
+			String expectedUsername, String expectedPassword) {
+		assertThat(credentials.getUserName(), equalTo(expectedUsername));
+		assertThat(credentials.getPassword(), equalTo(expectedPassword.toCharArray()));
+	}
+
 	@Configuration
 	@EnableConfigurationProperties(MongoProperties.class)
 	static class Conf {