To refine the clinical and radiologic description of an unusual benign disease, cystic pyeloureteritis (CPU), consisting of the appearance of suburothelial cysts that raise the mucosa layer of the urothelium. We also studied its relationship with various types of inflammation, including chronic infection, that may be the stimulus for the appearance of CPU. We compiled 34 cases of CPU covering the period 1976 to 1994, analyzing the clinical manifestations, diagnostic procedures, differential diagnosis, and evolution. There are no specific symptoms associated with the presence of cysts. The average age of the patients was 59 years (range 30 to 77). Urinary tract infection was detected in 18 (53%). The pyeloureteritis was unilateral in 27 (79%) and bilateral in 7 (21%) of the patients. The location of the cysts was as follows: 1 pyelic (3%); 6 pyeloureteral (18%); and 27 (79%) ureteral. Resolution of the radiologic alterations depends on the resolution of the associated pathology: infections, lithiasis, and obstruction. We conclude that CPU is a benign pathology with indolent evolution and variable duration; it is not associated with sequelae. Diagnosis is made on the basis of radiologic findings, mainly intravenous urography; in view of the minor entity of the pathology, biopsy is not advisable if the radiologic findings are conclusive.