One hundred and nine male patients took part in a randomized trial of elective suprapubic or urethral catheterization in retention of urine. The self-retaining trocar suprapubic catheter proved safe and reliable in trained hands and its use was associated with a low incidence of side effects. The suprapubic catheter when used to allow continuous flow resection appeared to lead to decreased blood loss and reduced resection time. No decrease in urinary infection rate over the period of hospital stay was noted in the suprapubic group. The suprapubic catheter was more comfortable than the urethral and also allowed a trial of voiding prior to removal. Use of the suprapubic catheter was not associated with an increased hospital stay.