Pigmented villonodular synovitis (PVNS) is a rare disease, with multiple forms, anatomic sites, and treatment methods having been described. During a 10-year period, 14 patients, 7 male and 7 female, average age 35 years (range, 19 to 64 years) were treated for PVNS with arthroscopic partial or total synovectomy. Average follow-up was 42 months (range, 8 to 83 months). Twelve patients had diffuse and 2 had a localized form. Results were assessed subjectively, clinically, and radiographically, and were rated as excellent, good, fair, or poor. There were no complications and 10 patients (72%) were rated as excellent or good, 2 patients (14%) as fair, and 2 patients (14%) as poor. The recurrence rate was 14% and occurred in the group with diffuse PVNS. Radiographs did not show any bone erosion. The most widely accepted treatment for PVNS is synovectomy, and both open and arthroscopic synovectomy have been advocated as treatment. Advantages of arthroscopic treatment include accurate evaluation of the knee joint, treatment of other pathology, more rapid rehabilitation, decreased risk of joint stiffness, and less pain. In our experience, it appears that arthroscopic synovectomy is an effective method of treatment of this disorder.