A comprehensive survey of Japanese patients with adult Still's disease was made by questionnaire which was sent to major institutions with rheumatology units in Japan. Of 146 cases from 32 institutions, 90 were judged to be definitely diagnosed as adult Still's disease. The major clinical features in these 90 patients consisted of high fever, polyarthralgia, rash, increased erythrocyte sedimentation rate, negative autoantibodies, leukocytosis, liver dysfunction, and hyperferritinemia. The incidence of several features showed significant differences between these cases and previous nonJapanese cases.