No characteristic clinical presentation of pigmented villonodular synovitis of the shoulder can yet be determined. Symptoms of discomfort and stiffness may appear insidiously or, in some cases, pigmented villonodular synovitis may be found incidentally during surgery for unrelated problems. Cystic and degenerative changes are more likely to occur in the shoulder than in joints with large synovial recesses such as the knee. Histologic findings parallel those in other joints. Optimal treatment appears to be early marginal excision for the localized form or total synovectomy for the diffuse form. The incidental finding of pigmented villonodular synovitis should not influence the decision to proceed with a preplanned reconstructive procedure. No experience with arthroscopic treatment or radiation therapy for diffuse pigmented villonodular synovitis of the shoulder has been reported.