1. The results of synovectomy of the knee in eighty-five patients with rheumatoid arthritis are presented.

2. When reviewed between five and nine years after operation 55 per cent of 122 knees still had improvement in pain.

3. Only 31 per cent of knees lost movement.

4. Recurrence of symptoms in nearly all cases was related to the recurrence of active rheumatoid synovitis.

5. Recurrence of symptoms was a little less likely when the generalised disease improved, when the Rose-Waaler test was negative, when only one knee was involved and when the operation had been carried out within three years of the onset of disease in that knee.