Ten patients underwent bilateral sagittal split ramus osteotomy for the correction of mandibular retrognathia. Prior to the surgery, predictive cephalometric tracings were completed, utilizing horizontal and vertical reference guides. The anticipated horizontal and vertical changes were determined from the predictive tracings, and these results were recorded on the prediction tracing. During surgery, corresponding reference marks were made on the lateral surface of the mandible. These reference marks were utilized to position the proximal segment during surgery, prior to placement of stabilization screws. A postoperative lateral cephalometric radiograph was taken within 24 hours in each case. The positions of the proximal segments were compared pre- and postsurgically. The results of this study indicate that this simple method results in accurate positioning of the proximal segments.