Adult Still's Disease (SD) has evolved into a well-characterized nosologic entity. This categorization allows physicians to place a unifying label on the rare, puzzling patient who presents with a systemic illness characterized by high spiking fever of unknown cause associated with intense arthralgias or arthritis, an evanescent erythematous macular or maculopapular rash, and other less constant features of systemic illness including lymphadenopathy, hepatosplenomegaly, sore throat, leukocytosis, anemia and elevated concentration of hepatic enzymes. The diagnosis of Adult SD is syndromic, based solely on compatible clinical findings; serologic or other diagnostic tests do not aid in diagnosis. The diagnostic problem presented by these patients with such severe systemic illness and the insecurities inherent in diagnosis based solely on clinical features make the availability of the diagnosis, Adult SD, useful in patient care. The cause of Adult SD is unknown. Some have speculated that the disease has features of non-necrotizing immune complex vasculitis. Rubella infection has been reported to be associated with Adult SD, but no clear-cut etiologic relationship has been established. Neither rubella infection nor any other potential antigen has been identified consistently in association with the disease. Management of patients with the disease depends on the correct diagnosis. Diagnosis should include recognition of the syndrome as well as exclude other possible diseases. Control of systemic manifestations may require unusually high doses of aspirin, indomethacin or other non-steroidal anti-inflammatory drugs, prednisone or combinations of these drugs. Some adults appear to require both high-dose prednisone and indomethacin to control disease manifestations. Fortunately, systemic attacks are usually episodic; steroid toxicity can be minimized by use of alternate day doses and attempts to discontinue steroids between episodes. The current series and other reports of long-term follow-up indicate that Adult SD may be more disabling than was originally reported. At least three patterns of recurrences occur: 1) systemic attacks with or without arthritis, 2) pauciarticular disease, and 3) disabling deforming chronic arthritis, which may require surgery and long-term anti-inflammatory, gold, or cytotoxic therapy.