The effect of microinjection of 6-hydroxydopamine into the preoptic area was studied to observe the effect of destruction of catecholaminergic terminals in the preoptic area on acupuncture analgesia. It was shown that the analgesic effect of acupuncture was significantly enhanced in 6-hydroxydopamine treated group on the second and fourth day after injection as compared with those before injection or those in control group. The fluorecence of catecholamine terminals in the preoptic area disappeared almost completely on the fourth day after injection, and did not restore on the tenth day. The data indicate that the reduction of catecholamine content in the preoptic area may enhance acupuncture analgesia.