Synovectomy of the knee for the control of recurrent hemarthrosis was performed in thirteen patients with hemophilic arthropathy. Preoperatively, all patients had experienced an average of three bleeding episodes into the affected joint per month, and had been unresponsive to at least six months of medical management. Radiographically, all knees had either Stage-II or Stage-III hemophilic arthropathy. The average age of the patients at the time of synovectomy was sixteen years and the average length of follow-up was 7.3 years (range, two to eleven years and seven months). Although the motion of the knee remained unchanged postoperatively in two patients, ten patients had an average loss of 41 degrees. One patient eventually required an arthrodesis. Radiographically, there was slight further joint deterioration after synovectomy, and no knee progressed beyond Stage-III hemophilic arthropathy. Only one patient in our series had a recurrent spontaneous hemarthrosis of the synovectomized knee, although two others had traumatic bleeding episodes. The complications included three immediate postoperative hemarthrosis requiring surgical evacuation, isoimmune hemolytic anemia in one patient, patellofemoral adhesions in two knees, and a total fibrous ankylosis that required a knee arthrodesis in one patient. It was concluded from our study that chronic recurrent hemarthrosis and the pain associated with persistent synovitis in the hemophilic knee can be effectively eliminated for as many as twelve years after open synovectomy, although usually with significant loss of motion of the knee. This procedure also appeared to slow the progression of arthropathy, and no patient had been considered for a total knee replacement at the time of writing.