Pigmented villonodular synovitis is a specific lesion of the synovial membrane of the joint and bursal mucosa. In recent years it is frequently regarded as tumor like disease. The problem of therapy of the diffuse form of the disease is yet to be solved. Recurrence rates after partial synovial capsulectomy remain high (33-46%) as well as after operation combined with radiation therapy. The authors summed up their experience in combined therapy of pigmented villonodular synovitis. The method was used in 24 patients with the diffuse form of the disease, ranging in age from 15 to 62. In 18 of 24 patients the process affected the knee joint, in 6 patients the articular bones were involved in the process. Partial synovial capsulectomy with subsequent development of recurrences was recorded in 14 patients' history. Total synovial capsulectomy was performed at the first stage; in knee joint involvement the operation was supplemented by meniscectomy. gamma-beam therapy followed operation in 3-4 weeks. Radiotherapy was necessitated by the fact that elements of the affected synovial sheath could not be completely removed even in total synovial capsulectomy. Irradiation was given from 2 fields, a single focal dose being 1.2-1.5 Gy, 5 fractions a week; a summary focal dose reached 16-20 Gy. A follow up period lasted from 6 mos to 6 yrs. Complete convalescence was noted in 23 patients. Occupational rehabilitation was achieved in 21 patients. In 2 patients the functional outcome was considered to be satisfactory. The data obtained indicated to a high efficacy of combined therapy of the diffuse form of pigmented villonodular synovitis and the appropriateness of the use of radiotherapy in the postoperative period.