To the Editor: I would like to commend the authors of “Effect of Transcutaneous Electrical Nerve Stimulation on Human Blood β-Endorphin Levels,” for their ambitious undertaking.1 It is necessary that studies like this one be undertaken. It is unfortunate, however, that the plethora of transcutaneous electrical nerve stimulation (TENS) and acupuncture literature was largely ignored by the authors and the study suffered for it. As a professor of electrotherapy, I come across very little literature suggesting that conventional TENS works at all through an endorphin-mediated pain pathway.2 Nor has this claim been made regarding low-rate TENS in general. Rather, strong, low-rate2 or acupuncture-like TENS has been hypothesized to work in this manner.3,4 Unfortunately, by ignoring this important distinction, the authors have emerged with a less than valuable study. The operative word in strong, low-rate is “strong.”… [ ARTICLE][1] [1]: /lookup/volpage/64/1367?iss=9