An experimental investigation of acupuncture's analgesic potency, separated from suggestion effects, is described, in which judgments of shock-elicited pain of the forearm were recorded along two separate scales: intensity and aversiveness. Data from experimental subjects, who received electrical acupunctural stimulation through surface electrodes located over acupuncture points and were given explicit counter-suggestions of sensitization, were compared to those obtained from control subjects, who received such stimulation over incorrect loci and were given explicit suggestions of analgesia. No alterations in the perception of pain intensity, either by acupunctural stimulation or suggestion, could be detected at any time during the experiment, but stimulation of the correct points produced a significant analgesic reduction in aversiveness which was specific to the arm so stimulated, overcame the counter-suggestion of sensitization, and persisted after stimulation was discontinued. No significant reductions were recorded from control subjects. These findings are interpreted in light of other experimental acupuncture research, and of the demonstrated mode of action of analgesics of proven efficacy.