A retrospective study was made of 122 patients who had an abdominoperineal excision (APE) of the rectum for carcinoma at Concord Hospital between 1971 and 1979. Fifty-two percent of patients suffered one or more significant urological complications. These included urinary tract infection (32%), operative trauma to the urinary tract (8.5%) and temporary or permanent bladder dysfunction in 35% of patients. Acute urinary retention, when temporary, was managed by simple measures. Chronic retention, incontinence and some episodes of acute retention were due to a neurogenic bladder. These patients were difficult to treat. It is recommended that urodynamic studies be used to assess these patients who develop a neurogenic bladder before any treatment is instituted. This is relevant especially in those patients in whom a transurethral resection of either the bladder neck or prostate is contemplated.