A patient who developed mutilans-type arthropathy, splenomegaly, leukopenia, leg ulcer and massive hydroxyapatite accumulation during the course of progressive systemic sclerosis (PSS) was reported. A 56-years-old female had suffered Raynaud's phenomenon since the beginning of her third decade. She developed multiple symmetrical arthritis and morning stiffness at the age of 29, and was treated with NSAIDs and low dose corticosteroids under the diagnosis of rheumatoid arthritis (RA) Because of dysphagia and diarrhea, she was admitted in Niigata-Kenritsu Senami Hospital in September, 1987. Physical and roentgenographic examinations revealed diffuse scleroderma, mutilans-type arthropathy, lung fibrosis, splenomegaly and right leg ulcer. Laboratory examinations showed leukopenia, high titer of anti-DNA antibody, positive anti-Scl-70 antibody and mild hypocomplementemia. These findings suggested that she had PSS and Felty's syndrome. Furthermore, massive subcutaneous and intraarticular hydroxyapatite accumulation were noticed. The leg ulcer and laboratory data gradually improved with the combination therapy of corticosteroids, D-penicillamine and plasmapheresis. Although it has been well recognized that PSS patients reveal frequently the articular lesions similar to these of RA, severe mutilans-type arthropathy seen in this case is extremely rare. The joint contracture might be induced by hydroxyapatite accumulation, of which the early diagnosis seems to be very important in long-standing PSS patients.