Positive preoperative urine cultures were obtained from 31 of 107 patients who underwent transurethral prostatectomy (TUR). The incidence was 59% among the patients who had had indwelling catheter and 15% in the non-catheterized cases. Of the 76 patients whose urine was sterile before TUR, 24 (32%) became infected in connection with the operation or in the immediate postoperative period. The length of hospital stay after TUR averaged 7.2 days for the patients with sterile urine postoperatively and 10.3 days for those with infected urine, a non-significant difference, partly explained by circumstances other than the infection. The postoperative urinary infections were not associated with serious complications. Postoperative epididymitis occurred in three patients. The mortality was nil.