The objective of this study is to evaluate the clinical features and prognosis of adult-onset Still's disease (AOSD). One hundred and four AOSD patients who were analyzed retrospectively were enrolled in this study. Medical charts were systematically reviewed for: demographic data, clinical features, laboratory findings, treatments, and outcomes. The major clinical features were: spiking fever 100%, evanescent maculopapular rash 95%, polyarthralgia 90%, sore throat 78%, lymphadenopathy 66%, hepatosplenomegaly 57%, hydrohymenitis 30%, neutrophilia 98%, liver disfunction 62%, increased erythrocyte sedimentation rate (ESR) 96%, and hyperferritinaemia 99%. Reactive hyperplasia was shown in all patients who underwent lymph node biopsy. Ninety-five percent and 63% of the patients were treated with glucocorticoid and immune suppressant, respectively. Those with prednisone or its equivalent dosage of > or =0.8 mg/kg/d achieved quicker remission and less relapse. Persistent fever, evanescent rash, arthritis, and sore throat were the most prevalent symptoms in patients with AOSD, with laboratory findings of leukocytosis, elevated liver enzymes, elevated ESR and serum ferritin. Glucocorticoid and immune suppressive drugs are effective for AOSD; however, the relapsing rate is relatively high. High levels of white blood cells, serum ferritin and ESR, as well as glucocorticoid dosage were related to relapse.