diff --git a/nset.go b/nset.go
index 85247ef..086c20f 100644
--- a/nset.go
+++ b/nset.go
@@ -140,6 +140,28 @@ func (n *NSet[T]) GetBitMask(x T) StorageType {
 	return 1 << (((x << BucketIndexingBits) >> BucketIndexingBits) % StorageTypeBits)
 }
 
+func (n *NSet[T]) Union(otherSet *NSet[T]) {
+
+	for i := 0; i < BucketCount; i++ {
+
+		b1 := &n.Buckets[i]
+		b2 := &otherSet.Buckets[i]
+
+		if b1.StorageUnitCount < b2.StorageUnitCount {
+
+			storageUnitsToAdd := b2.StorageUnitCount - b1.StorageUnitCount
+			b1.Data = append(b1.Data, make([]StorageType, storageUnitsToAdd)...)
+
+			b1.StorageUnitCount += storageUnitsToAdd
+			n.StorageUnitCount += storageUnitsToAdd
+		}
+
+		for j := 0; j < len(b1.Data) && j < len(b2.Data); j++ {
+			b1.Data[j] |= b2.Data[j]
+		}
+	}
+}
+
 func (n *NSet[T]) GetIntersection(otherSet *NSet[T]) *NSet[T] {
 
 	outSet := NewNSet[T]()
diff --git a/nset_test.go b/nset_test.go
index 69aa818..a51acce 100755
--- a/nset_test.go
+++ b/nset_test.go
@@ -27,9 +27,6 @@ func TestNSet(t *testing.T) {
 	n1.Add(63)
 	n1.Add(math.MaxUint32)
 
-	// 4294967295
-	// 4294967295
-
 	AllTrue(t, n1.Contains(0), n1.Contains(1), n1.Contains(63), n1.Contains(math.MaxUint32), !n1.Contains(10), !n1.Contains(599))
 	AllTrue(t, n1.ContainsAll(0, 1, 63), !n1.ContainsAll(9, 0, 1), !n1.ContainsAll(0, 1, 63, 99))
 	AllTrue(t, n1.ContainsAny(0, 1, 63), n1.ContainsAny(9, 99, 999, 1), !n1.ContainsAny(9, 99, 999))
@@ -59,6 +56,18 @@ func TestNSet(t *testing.T) {
 
 	n4n5 := n4.GetIntersection(n5)
 	AllTrue(t, n4n5.ContainsAll(0, 1, 64, math.MaxUint32), !n4n5.Contains(63))
+
+	//Union
+	n6 := nset.NewNSet[uint32]()
+	n6.AddMany(4, 7, 100, 1000)
+
+	n7 := nset.NewNSet[uint32]()
+	n7.AddMany(math.MaxUint32)
+	n7OldStorageUnitCount := n7.StorageUnitCount
+	n7.Union(n6)
+
+	AllTrue(t, n6.ContainsAll(4, 7, 100, 1000), !n6.Contains(math.MaxUint32), n7.ContainsAll(4, 7, 100, 1000, math.MaxUint32), n7.StorageUnitCount == n7OldStorageUnitCount+n6.StorageUnitCount)
+
 }
 
 func TestNSetFullRange(t *testing.T) {