The role of arthroscopic meniscectomy in middle-aged patients has not previously been evaluated. This paper reports on 73 knees in 68 patients aged over 40, all of whom were shown arthroscopically to have meniscal tears and who were felt to be suitable candidates for meniscectomy. Many of these patients had typical traumatic meniscal tears, and if no degenerative joint changes were present at the time of meniscectomy, 95 per cent of them had good or excellent results an average of two and a half years later. In those instances where degenerative joint changes were present, removal of the offending segment of torn meniscus produced 80 per cent good or excellent results over the same period of time. These facts seem important now that arthroscopy permits such precise diagnosis of meniscal tears and of joint degeneration.