Eight patients subjected tosagittal split ostcotomy with A.O.miniplates and the results were rcported.The averagc operation time was 240.6 minutes, and the average blood loss was 290.6ml. Paresthesia of the lower lip and men tal area was observcd in patients, and the period for recovery exceeded 1 year in 15 out of 16 sides. However the range and scope of parcsthesia showed anarrowing tendency. The poriod of intcrmaxillary fixation was shorter than in wire osteos ynthesis. A. O. miniplates were removcd on 5 sides in 4 patients. The reasons were sense of incongmity, dull pain and infection. The appcarance of T. M. J. symptoms was rare. Repositioning techniques of the extemal fragments wereapplied and fbund to boeffective. Relapse and changes on latcral ccphalogmms X-ray photo, between opemtion and 1 year after operation, were minimized.