diff --git a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Criteria.java b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Criteria.java
index 627236b47..4ce58f14a 100644
--- a/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Criteria.java
+++ b/spring-data-mongodb/src/main/java/org/springframework/data/mongodb/core/query/Criteria.java
@@ -20,14 +20,15 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.regex.Pattern;
 
+import org.bson.BSON;
 import org.bson.types.BasicBSONList;
 import org.springframework.data.mongodb.InvalidMongoDbApiUsageException;
 import org.springframework.data.mongodb.core.geo.Circle;
 import org.springframework.data.mongodb.core.geo.Point;
 import org.springframework.data.mongodb.core.geo.Shape;
 import org.springframework.util.Assert;
-import org.springframework.util.StringUtils;
 
 import com.mongodb.BasicDBObject;
 import com.mongodb.DBObject;
@@ -97,13 +98,17 @@ public class Criteria implements CriteriaDefinition {
 			throw new InvalidMongoDbApiUsageException(
 					"Multiple 'is' values declared. You need to use 'and' with multiple criteria");
 		}
-		if (this.criteria.size() > 0 && "$not".equals(this.criteria.keySet().toArray()[this.criteria.size() - 1])) {
+		if (lastOperatorWasNot()) {
 			throw new InvalidMongoDbApiUsageException("Invalid query: 'not' can't be used with 'is' - use 'ne' instead.");
 		}
 		this.isValue = o;
 		return this;
 	}
 
+	private boolean lastOperatorWasNot() {
+		return this.criteria.size() > 0 && "$not".equals(this.criteria.keySet().toArray()[this.criteria.size() - 1]);
+	}
+
 	/**
 	 * Creates a criterion using the $ne operator
 	 * 
@@ -269,7 +274,11 @@ public class Criteria implements CriteriaDefinition {
 	 * @return
 	 */
 	public Criteria not() {
-		criteria.put("$not", null);
+		return not(null);
+	}
+
+	private Criteria not(Object value) {
+		criteria.put("$not", value);
 		return this;
 	}
 
@@ -280,8 +289,7 @@ public class Criteria implements CriteriaDefinition {
 	 * @return
 	 */
 	public Criteria regex(String re) {
-		criteria.put("$regex", re);
-		return this;
+		return regex(re, null);
 	}
 
 	/**
@@ -292,13 +300,32 @@ public class Criteria implements CriteriaDefinition {
 	 * @return
 	 */
 	public Criteria regex(String re, String options) {
-		criteria.put("$regex", re);
-		if (StringUtils.hasText(options)) {
-			criteria.put("$options", options);
+		return regex(toPattern(re, options));
+	}
+
+	/**
+	 * Syntactical sugar for {@link #is(Object)} making obvious that we create a regex predicate.
+	 * 
+	 * @param pattern
+	 * @return
+	 */
+	public Criteria regex(Pattern pattern) {
+
+		Assert.notNull(pattern);
+
+		if (lastOperatorWasNot()) {
+			return not(pattern);
 		}
+
+		this.isValue = pattern;
 		return this;
 	}
 
+	private Pattern toPattern(String regex, String options) {
+		Assert.notNull(regex);
+		return Pattern.compile(regex, options == null ? 0 : BSON.regexFlags(options));
+	}
+
 	/**
 	 * Creates a geospatial criterion using a $within $center operation. This is only available for Mongo 1.7 and higher.
 	 * 
@@ -426,16 +453,17 @@ public class Criteria implements CriteriaDefinition {
 		DBObject dbo = new BasicDBObject();
 		boolean not = false;
 		for (String k : this.criteria.keySet()) {
+			Object value = this.criteria.get(k);
 			if (not) {
 				DBObject notDbo = new BasicDBObject();
-				notDbo.put(k, this.criteria.get(k));
+				notDbo.put(k, value);
 				dbo.put("$not", notDbo);
 				not = false;
 			} else {
-				if ("$not".equals(k)) {
+				if ("$not".equals(k) && value == null) {
 					not = true;
 				} else {
-					dbo.put(k, this.criteria.get(k));
+					dbo.put(k, value);
 				}
 			}
 		}
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateTests.java
index 06e59d737..eed2aedfd 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/MongoTemplateTests.java
@@ -46,9 +46,9 @@ import org.springframework.data.mongodb.MongoDbFactory;
 import org.springframework.data.mongodb.core.convert.CustomConversions;
 import org.springframework.data.mongodb.core.convert.MappingMongoConverter;
 import org.springframework.data.mongodb.core.index.Index;
+import org.springframework.data.mongodb.core.index.Index.Duplicates;
 import org.springframework.data.mongodb.core.index.IndexField;
 import org.springframework.data.mongodb.core.index.IndexInfo;
-import org.springframework.data.mongodb.core.index.Index.Duplicates;
 import org.springframework.data.mongodb.core.mapping.MongoMappingContext;
 import org.springframework.data.mongodb.core.query.Criteria;
 import org.springframework.data.mongodb.core.query.Order;
@@ -131,6 +131,7 @@ public class MongoTemplateTests {
 		template.dropCollection(template.getCollectionName(PersonWithIdPropertyOfTypeLong.class));
 		template.dropCollection(template.getCollectionName(PersonWithIdPropertyOfPrimitiveLong.class));
 		template.dropCollection(template.getCollectionName(TestClass.class));
+		template.dropCollection(Sample.class);
 	}
 
 	@Test
@@ -1084,10 +1085,33 @@ public class MongoTemplateTests {
 		assertThat(template.findOne(query(where("id").is(id)), Sample.class), is(nullValue()));
 	}
 
+	/**
+	 * @see DATAMONGO-423
+	 */
+	@Test
+	public void executesQueryWithNegatedRegexCorrectly() {
+
+		Sample first = new Sample();
+		first.field = "Matthews";
+
+		Sample second = new Sample();
+		second.field = "Beauford";
+
+		template.save(first);
+		template.save(second);
+
+		Query query = query(where("field").not().regex("Matthews"));
+		System.out.println(query.getQueryObject());
+		List<Sample> result = template.find(query, Sample.class);
+		assertThat(result.size(), is(1));
+		assertThat(result.get(0).field, is("Beauford"));
+	}
+
 	public static class Sample {
 
 		@Id
 		String id;
+		String field;
 	}
 
 	static class TestClass {
diff --git a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/query/QueryTests.java b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/query/QueryTests.java
index 8c074e6dc..5c9660a57 100644
--- a/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/query/QueryTests.java
+++ b/spring-data-mongodb/src/test/java/org/springframework/data/mongodb/core/query/QueryTests.java
@@ -100,7 +100,7 @@ public class QueryTests {
 	public void testComplexQueryWithMultipleChainedCriteria() {
 		Query q = new Query(where("name").regex("^T.*").and("age").gt(20).lt(80).and("city")
 				.in("Stockholm", "London", "New York"));
-		String expected = "{ \"name\" : { \"$regex\" : \"^T.*\"} , \"age\" : { \"$gt\" : 20 , \"$lt\" : 80} , "
+		String expected = "{ \"name\" : { \"$regex\" : \"^T.*\" , \"$options\" : \"\"} , \"age\" : { \"$gt\" : 20 , \"$lt\" : 80} , "
 				+ "\"city\" : { \"$in\" : [ \"Stockholm\" , \"London\" , \"New York\"]}}";
 		Assert.assertEquals(expected, q.getQueryObject().toString());
 	}
@@ -134,7 +134,7 @@ public class QueryTests {
 	@Test
 	public void testQueryWithRegex() {
 		Query q = new Query(where("name").regex("b.*"));
-		String expected = "{ \"name\" : { \"$regex\" : \"b.*\"}}";
+		String expected = "{ \"name\" : { \"$regex\" : \"b.*\" , \"$options\" : \"\"}}";
 		Assert.assertEquals(expected, q.getQueryObject().toString());
 	}