This patient presented with a fever of unknown origin and a constellation of other symptoms. After multiple infectious, common collagen vascular disorders and malignancy were excluded, the diagnosis of adult-onset Still's disease (AOSD) was entertained. AOSD is a rare systemic inflammatory disorder of unknown etiology and is classically characterized by “quotidian or double-quotidian” fever, arthritis/ arthralgia, and a salmon-pink evanescent rash. The estimated incidence of AOSD is 0.16 cases per 100,000 persons per year. The disease tends to affect younger people; in three-quarters of patients, the onset is between 16 and 35 years of age. Interestingly, an epidemiologic survey from Japan found that 67% of the patients presented after the age of 35 years. Fever is present in most AOSD patients (94 to 100%), and arthralgia/arthritis is found in majority of patients (64 to 100%). Other manifestations include myalgias (56 to 84%), rash (51 to 94%), pharyngitis (35 to 92%), splenomegaly (14 to 65%), lymphadenopathy (32 to 74%), pleuritis (12 to 53%), and pericarditis (10 to 37%). Diffuse pulmonary hemorrhage has been reported in a case of juvenile rheumatoid arthritis, of which Still's disease is considered to be a systemic form. Laboratory values usually reveal leukocytosis; in a series of 62 patients, one-third of patients had a WBC count of > 20 × 103 cells/μL. The ESR and CRP concentration are always elevated. A serum ferritin level of > 1,000 ng/mL has been used to suggest ASOD, although a reduction of its glycosylated fraction (< 20%) is more specific as a diagnostic marker. Other conditions that could be associated with an elevation of serum ferritin level to > 1,000 ng/mL include hereditary hemochromatosis, hereditary hyperferritinemia-cataract syndrome, chronic liver diseases, autoimmune disease-associated hemophagocytic syndrome, and insulin-resistant or metabolic syndrome. Unlike other systemic rheumatic diseases, the diagnostic criteria for ASOD include a negative test result for ANA and RF. Treatment depends on the acuity and severity of illness, and includes nonsteroidal antiinflammatory drugs, steroids, disease-modifying antirheumatic drugs such as methotrexate, IV Ig, anti-tumor necrosis factor agents (eg, infliximab or etanercept), anakinra (interleukin-1 receptor inhibitor) and rituximab (CD20 antibody). The clinical course can follow three different patterns, as follows: (1) a self-limited or monocyclic pattern, with most patients achieving remission within 1 year; (2) an intermittent or polycyclic systemic pattern with recurrent flares and complete remission between flares; and (3) a chronic pattern that is dominated by articular manifestations, which can be severe and can lead to joint destruction.