A bacteriological survey of 50 consecutive patients undergoing transurethral resection of the prostate was performed. Preoperatively, 28% of the patients had asymptomatic bacteriuria. In the postoperative period, 46% of all the patients developed transient bacteremia. A significantly higher rate of bacteremia was found in patients with hypertrophy of the prostate than in those with cancer of the prostate and in patients undergoing long-lasting surgical intervention. Patients who developed bacteremia due to pathogenic bacteria were hospitalized for a significantly longer period of time.