We report 60 synovectomies of the knee in 51 children with juvenile chronic arthritis. Synovitis had been present for an average of 5 years and the average age at operation was 13 years. Results were evaluated in terms of pain, knee movement, relapse of synovitis and radiological change during a follow-up averaging 7.5 years. The relief of pain was rewarding and there was a slight postoperative gain in range of knee movement in most cases. The older the patient at onset of disease, the greater the risk of pain during follow-up. Progressive joint destruction was more common in younger patients, those with systemic or polyarticular disease, and those with highly active disease at the time of operation. Recurrence of synovitis was more frequent in patients who had their operation in a phase of high disease activity; this occurred most often in patients with polyarticular disease.