Rapid maxillary expansion (RME) occupies unique niche in dentofacial therapy. Rapid Maxillary expansion or Split palate is a skeletal type of expansion that involves the separation of the mid-palatal suture and movement of the maxillary shelves away from each other.The stability of this procedure have thrown a new light on its clinical application. Whether it is slow, rapid or semi rapid expansion, proper diagnosis and case assessment is very essential to ensure consistent results. Maxillary expansion is indicated in a variety of clinical situations and we have reviewed the different mechanisms available to clinicians. The precise method selected will depend on the nature of the malocclusion present