Surgery on the upper abdomen is associated with marked postoperative pulmonary dysfunction largely due to restriction of lung expansion secondary to incisional pain. Groups (3) of patients (a control group, a sham group and a group receiving transcutaneous electric nerve stimulation [TENS] for pain control) were studied to determine whether this modality is effective in alleviating postoperative pain. Spirometry, arterial blood gases, clinical and radiologic evidence of postoperative pulmonary complications and the frequency of analgesic requests were determined. Of 40 patients the 15 receiving TENS required only 4.7 .+-. 2.5 doses of narcotic analgesics in the 1st 72 h as opposed to 10.1 .+-. 2.7 and 10.4 .+-. 2.7 in the other 2 groups (P < 0.005). There were 6 postoperative pulmonary complications, all occurring in the groups not receiving TENS. Postoperative arterial Po2 [O2 partial pressure], vital capacity and functional residual capacity were least depressed in the TENS group. Apparently, TENS minimizes the tendency toward postoperative alteration in respiratory mechanics and decreases the incidence of pulmonary complications by alleviating incisional pain.