There are many procedures for the treatment of acute A-C injury which have many complic ation such as limitation of shoulder motion, post traumatic arthritis and recurrence of dislocation etc. From July 1992 to June 1996 at National Medical Center, 21 patients with A-C injury had been treated by modified Phemister operation. The mean follow up time was 14.6 months. The following results are obtained. 1. There was no limitation of shoulder motion in 20 cases. 2. The comparison of coraco-clavicular distance after surgery ( 2.24 mm ) with that of fallow up ( 3.95 mm ) showed no significant difference. 3. Clinical resuls showed that good in 18 cases, fair in 2 cases, poor in 1 case. From the above result, we suggest that Modified Phemister method is simple and good procedure in the treatment of acute A-C dislocation.