Authors conducted a clinical study on eleven knees of nine patients which had been treated with modified Maquet operation for patellofemoral malalignment synd- rome and followed up average 22.5 months (range from 10 months to 35 months). Their indication for surgery were failure of conservative treatment including qua driceps strengthening, non-steroid antiinflammatory drugs and reassurance during six months. Clinical assessments of these cases were made according to modified patellofemoral pain and instability scoring of Lysholms and congruence angle change by Merchant view. The results were two excellent, three very good, three good, and one poor. Preoperative Q-angle was 25 degree and it changed to 8.5 degree postoperatively Preoperative congruence angle in Merchant view was +3.9 degree and it changed to -6.7 degree postoperatively. By these about results, authors suggest that modified Maquet operation was one of the good methods that can be done easily for anterior knee pain caused by patellofemoral malalignment syndrome.