Fifteen patients with adult onset Still's disease are described, all diagnosed according to recognized criteria. Mean delay in reaching a firm diagnosis was 16 months. Besides the typical clinical picture, there was a high frequency of pruriginous rash, one instance of overlapping polymyositis and recurrent systemic manifestations in most cases. Chronic polyarticular involvement predominated, with radiological progression particularly in wrist, proximal interphalangeal and hip joints. However, functional prognosis at the end of a mean 4.8-year course was satisfactory, as also the response to treatment mainly with steroid drugs and, on occasion, with remitting agents to alleviate arthritis.