The efficacy of transcutaneous electrical nerve stimulation (TENS) in relieving postoperative pain has been assessed by means of a prospective randomized controlled trial in 62 male patients undergoing unilateral inguinal herniorrhaphy. Thirty-four patients received TENS and 28 patients received sham TENS for 48 h after the operation. Pain was assessed by means of linear analogue pain scales, analgesic requirements and peak expiratory flow readings. We were unable to detect any significant differences in these variables when the two groups were compared. These results do not support the use of TENS.