During many procedures for supravesical urinary diversion, cystectomy is commonly not performed. In this series of 128 diversions in which the bladder remained in situ, 24 patients (18.7%) developed pyocystis, characterized by fever, urethral discharge, and abdominal complaints. Conservative efforts at eradicating the infection were unsuccessful and cystectomies were performed. One patient died. Three others had septic complications, but these and the 20 others without complications were relieved of their symptoms. The surgical approach is the treatment of choice. An aggressive approach is particularly recommended in those patients in whom the cerebrospinal fluid is shunted into the vascular system since even transient blood stream seeding from an infected focus may be life-threatening.