Two episodes of severe panniculitis accompanied by fever and an acute phase response were the main clinical features in a patient who had an unusual IgG kappa paraprotein. Both episodes responded promptly to steroids. Complement proteins of the early classical pathway were depleted in the patient's serum, and in vitro experiments indicated that the IgG kappa paraprotein activated complement directly. The association of recurrent panniculitis and paraproteinemia-hypocomplementemia has been described in 2 other patients. It should be recognized since its response to steroids is immediate.