Low-frequency electroacupuncture effectively alleviated recurrent pain in 10 patients. Basal levels of beta-endorphin and met-enkephalin in the lumbar cerebrospinal fluid (CSF) of these patients were not different from those in pain-free control subjects. After electroacupuncture in the patients with pain CSF beta-endorphin levels rose significantly in all subjects, but met-enkephalin levels were unchanged. These results suggest that the analgesia observed after electroacupuncture in patients with recurrent pain may be mediated by the release into the CSF of the endogenous opiate, beta-endorphin.