Objective. Lupus cystitis is a relatively rare complication of systemic lupus erythematosus (SLE). The clinical characterization of it remains obscure. We sought to provide insight for timely recognition and diagnosis of lupus cystitis, and for efficacious management of this disease entity. Methods. The clinical files of 18 patients with lupus cystitis treated at Peking Union Medical College Hospital were reviewed. Clinical manifestations, laboratory investigations, therapeutic measurements, and clinical outcomes were analyzed. Results. There were both male and female patients with a wide range of ages. The interval from onset of SLE to hydroureteronephrosis varied from 0 to 5 years. The most common clinical presentations were gastrointestinal (GI) symptoms, while urinary symptoms were less common and relatively-mild. Lupus nephritis often presented concomitantly with lupus cystitis but was relatively less active pathologically. Laboratory findings showed a high rate of positive anti-SSA. Therapy of prednisone plus cyclophosphamide was effective for lupus cystitis. Delayed diagnosis and treatment may lead to irreversible obstructive uropathy and permanent loss of renal function. Conclusion. Lupus cystitis may not be so rare as has been thought. The diagnosis of lupus cystitis should be considered when patients with SLE present with GI symptoms, and therapy should begin as early as possible. (First Release Jan 15 2011; J Rheumatol 2011;38:667-71; doi:10.3899/jrheum.100617)