When the space created by missing mandibular posterior teeth is not filled for a long period of time, elongation of the opposite dentoalveolar segments of the maxilla is usually demonstrable. This condition introduces difficulties in later prosthetic restoration. There are many ways to be used in the solution of the problems dependent upon the severity of elongation. When the elongation is severe, in order to gain sufficient interarch space for prosthetic resotration, extraction of those teeth is usually inevitable. However, as an alternative, posterior maxillary osteotomy was adopted in the present study to intrude the clongated segment to the functional position in harmony with the occlusal plane and to maintain tooth vitality. From observation of 15 cases of severely elongated maxillary posterior teeth, it is concluded that favorable results with good prognosis, can be achieved by using posterior maxillary osteotomy as a procedure.