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 caeb476a27f..14c829e9544 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
@@ -50,20 +50,22 @@ public class MongoProperties {
 	 */
 	public static final int DEFAULT_PORT = 27017;
 
+	public static final String DEFAULT_URI = "mongodb://localhost/test";
+
 	/**
-	 * Mongo server host.
+	 * Mongo server host. Cannot be set with uri.
 	 */
 	private String host;
 
 	/**
-	 * Mongo server port.
+	 * Mongo server port. Cannot be set with uri.
 	 */
 	private Integer port = null;
 
 	/**
-	 * Mongo database URI. When set, host and port are ignored.
+	 * Mongo database URI. Cannot be set with host, port and credentials.
 	 */
-	private String uri = "mongodb://localhost/test";
+	private String uri;
 
 	/**
 	 * Database name.
@@ -81,12 +83,12 @@ public class MongoProperties {
 	private String gridFsDatabase;
 
 	/**
-	 * Login user of the mongo server.
+	 * Login user of the mongo server. Cannot be set with uri.
 	 */
 	private String username;
 
 	/**
-	 * Login password of the mongo server.
+	 * Login password of the mongo server. Cannot be set with uri.
 	 */
 	private char[] password;
 
@@ -156,6 +158,10 @@ public class MongoProperties {
 		return this.uri;
 	}
 
+	public String determineUri() {
+		return (this.uri != null ? this.uri : DEFAULT_URI);
+	}
+
 	public void setUri(String uri) {
 		this.uri = uri;
 	}
@@ -180,7 +186,7 @@ public class MongoProperties {
 		if (this.database != null) {
 			return this.database;
 		}
-		return new MongoClientURI(this.uri).getDatabase();
+		return new MongoClientURI(determineUri()).getDatabase();
 	}
 
 	/**
@@ -198,6 +204,10 @@ public class MongoProperties {
 			Environment environment) throws UnknownHostException {
 		try {
 			if (hasCustomAddress() || hasCustomCredentials()) {
+				if (this.uri != null) {
+					throw new IllegalStateException("Invalid mongo configuration, " +
+							"either uri or host/port/credentials must be specified");
+				}
 				if (options == null) {
 					options = MongoClientOptions.builder().build();
 				}
@@ -215,7 +225,7 @@ public class MongoProperties {
 						credentials, options);
 			}
 			// The options and credentials are in the URI
-			return new MongoClient(new MongoClientURI(this.uri, builder(options)));
+			return new MongoClient(new MongoClientURI(determineUri(), builder(options)));
 		}
 		finally {
 			clearPassword();
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 51001affb07..5a89fbb378c 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
@@ -25,7 +25,9 @@ import com.mongodb.MongoCredential;
 import com.mongodb.ServerAddress;
 import com.mongodb.connection.Cluster;
 import com.mongodb.connection.ClusterSettings;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.ExpectedException;
 
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.test.util.EnvironmentTestUtils;
@@ -40,9 +42,13 @@ import static org.assertj.core.api.Assertions.assertThat;
  *
  * @author Phillip Webb
  * @author Andy Wilkinson
+ * @author Stephane Nicoll
  */
 public class MongoPropertiesTests {
 
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
 	@Test
 	public void canBindCharArrayPassword() {
 		// gh-1572
@@ -121,6 +127,30 @@ public class MongoPropertiesTests {
 		assertMongoCredential(credentialsList.get(0), "user", "secret", "test");
 	}
 
+	@Test
+	public void uriCannotBeSetWithCredentials() throws UnknownHostException {
+		MongoProperties properties = new MongoProperties();
+		properties.setUri("mongodb://127.0.0.1:1234/mydb");
+		properties.setUsername("user");
+		properties.setPassword("secret".toCharArray());
+		this.thrown.expect(IllegalStateException.class);
+		this.thrown.expectMessage("Invalid mongo configuration, " +
+				"either uri or host/port/credentials must be specified");
+		properties.createMongoClient(null, null);
+	}
+
+	@Test
+	public void uriCannotBeSetWithHostPort() throws UnknownHostException {
+		MongoProperties properties = new MongoProperties();
+		properties.setUri("mongodb://127.0.0.1:1234/mydb");
+		properties.setHost("localhost");
+		properties.setPort(4567);
+		this.thrown.expect(IllegalStateException.class);
+		this.thrown.expectMessage("Invalid mongo configuration, " +
+				"either uri or host/port/credentials must be specified");
+		properties.createMongoClient(null, null);
+	}
+
 	@Test
 	public void allMongoClientOptionsCanBeSet() throws UnknownHostException {
 		MongoClientOptions.Builder builder = MongoClientOptions.builder();
diff --git a/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc b/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc
index 03965be77b2..561b097b88d 100644
--- a/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc
+++ b/spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc
@@ -553,12 +553,12 @@ content into your application; rather pick only the properties that you need.
 	spring.data.mongodb.database=test # Database name.
 	spring.data.mongodb.field-naming-strategy= # Fully qualified name of the FieldNamingStrategy to use.
 	spring.data.mongodb.grid-fs-database= # GridFS database name.
-	spring.data.mongodb.host=localhost # Mongo server host.
-	spring.data.mongodb.password= # Login password of the mongo server.
-	spring.data.mongodb.port=27017 # Mongo server port.
+	spring.data.mongodb.host=localhost # Mongo server host. Cannot be set with uri.
+	spring.data.mongodb.password= # Login password of the mongo server. Cannot be set with uri.
+	spring.data.mongodb.port=27017 # Mongo server port. Cannot be set with uri.
 	spring.data.mongodb.repositories.enabled=true # Enable Mongo repositories.
-	spring.data.mongodb.uri=mongodb://localhost/test # Mongo database URI. When set, host and port are ignored.
-	spring.data.mongodb.username= # Login user of the mongo server.
+	spring.data.mongodb.uri=mongodb://localhost/test # Mongo database URI. Cannot be set with host, port and credentials.
+	spring.data.mongodb.username= # Login user of the mongo server. Cannot be set with uri.
 
 	# DATA REDIS
 	spring.data.redis.repositories.enabled=true # Enable Redis repositories.