Adult-onset Still disease (AOSD) is an uncommon inflammatory condition of unknown origin typically characterized by four main (cardinal) symptoms: spiking fever > or =39 degrees C, arthralgia or arthritis, skin rash and hyperleucocytosis (> or =10,000 cells/mm3) with neutrophils > or =80%. As many other manifestations are possible, diagnosis is potentially challenging. Determination of the total and glycosylated ferritin levels, although not pathognomonic, can help in diagnosis. The disease evolution of AOSD can be monocyclic, polycyclic or chronic. In chronic disease, joint involvement is often predominant and erosions are noted in one-third of patients. No prognostic factors have been identified to date. Therapeutic strategies are from observational data. Corticosteroids are usually the first-line treatment. With inadequate response to corticosteroids, methotrexate appears the best choice to control disease activity and allow for tapering of steroid use. For refractory disease, biological therapy with agents blocking interleukin-1 (anakinra) and then those blocking interleukin-6 (tocilizumab) seem the most promising.