A prospective randomized double-blind study was undertaken to evaluate the efficacy of transcutaneous nerve stimulation (TNS) in relief of acute post-thoracotomy pain by comparing postoperative narcotic requirements in 22 patients having TNS and in 22 patients having sham electrical stimulation. All patients in both groups had intrathoracic malignancies. When TNS was used, 22.7% of the patients required no narcotics in the first 24 hr postoperatively. All patients having sham stimulation required postoperative narcotics.