Thirteen patients with generalized synovial chondromatosis of the knee were treated by either removal of the loose bodies alone (n = 5) or arthroscopic synovectomy (n = 8). The average follow-up was 38 months (range 23-61). There were three recurrences in the loose body removal group, which were subsequently treated by arthroscopic synovectomy. Statistical analysis of the results shows a significant improvement in pain, synovitis and effusion, range of movement, and function after either treatment. The group treated by arthroscopic synovectomy had significantly lower recurrence rates (p = 0.02). We recommend arthroscopic synovectomy for patients with generalized synovial chondromatosis. However, if loose bodies alone are removed, a recurrence can be successfully treated by an arthroscopic synovectomy.