Among the occlusal discrepancies, maxillary transverse deficiency is quite common in several reasons. The reasons are comprised of maxillary hypoplasia, thumb sucking habits, non-syndromic palatal synostosis and syndromal patients including cleft patients. Orthodontic treatment is used routinely to correct a deficiency in young patients while it has limitations for a skeletally mature patient. Surgical treatments help provide effective maxillary expansion to correct a deficiency in adults. Surgical methods can be categorized to segmental Le Fort I osteotomy and surgically assisted rapid maxillary expansion(SARME). Both methods seem successful but each method would have its own indication. We give a review on transverse maxillary deficiency and two surgical methods.