The clinical and laboratory features in six patients with adult Still's disease are presented and compared with those in 52 other cases gathered from the literature. Although there is no pathognomonic abnormality, the condition can be readily recognized by the striking constellation of clinical and laboratory abnormalities. The typical rash occurs in 90 per cent of the cases, arthritis in 88 per cent, a fever with temperatures of 40 degrees C or more in 83 per cent and leukocytosis of 18,000 cells/mm3 or more in 67 per cent. One or more ot the following are frequently found: lymphadenopathy (48 per cent), splenomegaly (45 per cent), pleuritis or pneumonitis (31 per cent) and pericarditis (26 per cent). The initial therapy of choice is high doses of nonsteroidal anti-inflammatory drugs. This is not an uncommon disease, as was once thought, and awareness of it will avoid unnecessary diagnostic procedures and delay in initiating therapy.