Adult onset Still's disease (AOSD) is a systemic inflammatory disease with unknown etiology and characterized by evanescent salmon pink rash, sore throat, liver dysfunction, lymphadenopathy, hepatosplenomegaly, arthritis, and leukocytosis. It is a diagnosis of exclusion; however, there are case reports in the literature about patients with malignancies and AOSD-like signs and symptoms. Here we report a patient with AOSD seems to be associated with sarcomatoid renal cell carcinoma. This phenomenon is not distinguishable from primary AOSD either in presentation or in treatment; except for the main purpose of the management should be targeted to the underlying malignancy.