1. It is suggested that slow recovery and post-operative effusion after meniscectomy may often be due to "scar friction" when the incision in the synovial membrane is in contact with the non-articular surface of the femoral condyle. 2. The advantages of a horizontal incision are discussed, particularly with regard to early recovery. 3. The results of one hundred and three cases of meniscectomy are analysed. An attempt to trace the cause of incompletely successful results in 25 per cent. of cases failed to show any relation to minor coincident lesions discovered at operation, or to the amount of meniscus removed.