diff --git a/primitiveCollections/src/main/java/org/lucares/collections/IntList.java b/primitiveCollections/src/main/java/org/lucares/collections/IntList.java
index 209465c..7fa8374 100644
--- a/primitiveCollections/src/main/java/org/lucares/collections/IntList.java
+++ b/primitiveCollections/src/main/java/org/lucares/collections/IntList.java
@@ -261,6 +261,26 @@ public final class IntList implements Serializable, Cloneable {
 		index = insertPosition;
 	}
 
+	/**
+	 * Retains all elements contained in the specified list.
+	 *
+	 * @param retain
+	 *            the elements to retain
+	 */
+	public void retainAll(final IntList retain) {
+		final int size = index;
+		int insertPosition = 0;
+		for (int i = 0; i < size; i++) {
+			final int current = data[i];
+			if (retain.indexOf(current) >= 0) {
+				// keep current element
+				data[insertPosition] = current;
+				insertPosition++;
+			}
+		}
+		index = insertPosition;
+	}
+
 	/**
 	 * Replaces all values in the list by applying {@code operator}.
 	 *
diff --git a/primitiveCollections/src/test/java/org/lucares/collections/IntListTest.java b/primitiveCollections/src/test/java/org/lucares/collections/IntListTest.java
index f45dcda..16e587c 100644
--- a/primitiveCollections/src/test/java/org/lucares/collections/IntListTest.java
+++ b/primitiveCollections/src/test/java/org/lucares/collections/IntListTest.java
@@ -626,7 +626,7 @@ public class IntListTest {
 	}
 
 	@Test
-	public void replaceAllOnEmptyList() {
+	public void testReplaceAllOnEmptyList() {
 		final IntList list = new IntList();
 
 		list.replaceAll(i -> i * 3);
@@ -634,7 +634,7 @@ public class IntListTest {
 	}
 
 	@Test
-	public void removeAll() {
+	public void testRemoveAll() {
 		final IntList list = IntList.of(-2, -1, 0, 1, 2, 3, 4, 5, 6);
 		final IntList remove = IntList.of(-1, 2, 4, 5);
 
@@ -644,7 +644,7 @@ public class IntListTest {
 	}
 
 	@Test
-	public void removeEmptyList() {
+	public void testRemoveEmptyList() {
 		final IntList list = IntList.of(1, 2, 3, 4, 5, 6);
 		final IntList remove = new IntList();
 
@@ -654,7 +654,7 @@ public class IntListTest {
 	}
 
 	@Test
-	public void removeAllFromEmptyList() {
+	public void testRemoveAllFromEmptyList() {
 		final IntList list = new IntList();
 		final IntList remove = IntList.of(1);
 
@@ -662,4 +662,34 @@ public class IntListTest {
 		Assert.assertArrayEquals(new int[] {}, list.toArray());
 		Assert.assertEquals(0, list.size());
 	}
+
+	@Test
+	public void testRetainAll() {
+		final IntList list = IntList.of(-2, -1, 0, 1, 2, 3, 4, 5, 6);
+		final IntList retain = IntList.of(-1, 2, 4, 5, 99);
+
+		list.retainAll(retain);
+		Assert.assertArrayEquals(new int[] { -1, 2, 4, 5 }, list.toArray());
+		Assert.assertArrayEquals(new int[] { -1, 2, 4, 5, 99 }, retain.toArray());
+	}
+
+	@Test
+	public void testRetainAllOnEmptyList() {
+		final IntList list = IntList.of();
+		final IntList retain = IntList.of(-1, 2, 4, 5, 99);
+
+		list.retainAll(retain);
+		Assert.assertArrayEquals(new int[] {}, list.toArray());
+		Assert.assertArrayEquals(new int[] { -1, 2, 4, 5, 99 }, retain.toArray());
+	}
+
+	@Test
+	public void testRetainAllFromEmptyList() {
+		final IntList list = IntList.of(-2, -1, 0, 1, 2);
+		final IntList retain = IntList.of();
+
+		list.retainAll(retain);
+		Assert.assertArrayEquals(new int[] {}, list.toArray());
+		Assert.assertArrayEquals(new int[] {}, retain.toArray());
+	}
 }