A patient is described with systemic lupus erythematosus and large painless ascites and pleural effusions. Pleural and peritoneal fluid complement levels were depressed, and DNA binding was elevated in the presence of normal serum values. Immunoglobulin and complement deposits were demonstrated in vessels of the pleura, peritoneum, and skin, along with histologic evidence of vasculitis. The relation of the ascites and pleural effusions to the presence of widespread vasculitis and local immune complex formation is discussed. These complications responded poorly to corticosteroid therapy but slowly resolved following the addition of an immunosuppressive agent.