This study was planned as a pilot study to determine to what extent acupuncture might help in severe cases of migraine and, if possible, to see whether the mechanism was endorphin mediated. The study was carried out on 16 subjects who had severe and regular migraine for more than five years (mean duration 24 years). The study lasted eight months and was divided into four blocks of two months each: pre-treatment, treatment block I, treatment block II, and post-treatment. It was double-blind and cross-over in design. Acupuncture was found to cause a significant change in the number of headaches and their duration, with 40% of the subjects showing a 50%-100% reduction. Although pain sensation was not altered, attacks were less severe and less often accompanied by nausea and vomiting. At no stage was there any difference between subjects receiving saline or naloxone so that the possibility of a non-endorphin mechanism must be considered.