Adult onset Still's disease (AOSD) is an uncommon acute systemic inflammatory disease of unknown origin. The clinical features include high spiking fever, arthralgia or arthritis, transient maculopapular rash, lymphadenopathy, hepatosplenomegaly, and serositis. The laboratory findings include leukocytosis(neutrophilia), elevation of AST, ALT, ESR, CRP and serum ferritin, and negative rheumatic factor and anti-nuclear antibody. We report a case of a 52-year old woman whom symptom is subsided after steroid use. (J Korean Acad Fam Med 2007;28: 210-213)