We report a case of erosion of an inflatable penile prosthesis reservoir int the bladder 4 years after implantation for organic impotence. In contrast to previously reported cases this complication was not associated with incontinence, urinary tract infection or a revision procedure. Microscopic hematuria was present but there was no pyuria. Diagnosis evaded radiographic and cystoscopic confirmation. Bladder erosion of the reservoir was discovered incidentally during treatment of bladder calculi.