Clinical and radiographic findings of cystitis are reported in six patients with systemic lupus erythematosus. All patients had clinical manifestations of cystitis; radiography showed the bladder capacities were reduced and the bladder walls were thickened and irregular. Ureterohydronephrosis was found in some patients. Abnormal clinical and roentgenographic findings were reversed with high-dose corticosteroid therapy. These patients had concomitant widespread multisystem manifestations, especially of the central nervous system and gastrointestinal tract. No explanation for the bladder findings could be found other than lupus erythematosus. Urinary bladder involvement may be a primary manifestation of systemic lupus erythematosus, sometimes overshadowed by other major organ system disease. Corticosteroids appear to reverse most of the acute manifestations but the long-term prognosis is not known and may not be favorable.