Adult-onset Still's disease is a systemic inflammatory disorder with a highly variable clinical course. Mild hepatitis and anemia are common manifestations. We describe a patient with adult Still's disease who developed a severe hepatitis and a life-threatening pure red cell aplasia. The hepatitis developed after treatment with NSAIDs was started. The patient was successfully treated with a combination of prednisone, cyclosporin, and methotrexate. Physicians should be aware that severe hepatitis and pure red cell aplasia can occur in adult Still's disease. We recommend a careful monitoring of liver functions in patients with adult Still's disease who are being treated with NSAIDs.