Abstract: Aconitum bulleyanum Diel is an herb which has been used as an anodyne in Yunnan province for a long time. Bulleyaconitine A (Bul), an active principle, was extracted from this herb. The analgesic action of Bul has been shown in this paper by using the following methods: mice writhing evoked by ip 0.7% acetic acid 10 ml/kg; mice hot plate (56℃); continuous pain stimuli elicited by sc formaldehyde in front paw⁽⁸⁾ and-rat tail-flick response to light irradiation. The relative analgesic effect of Bul was found to be 1.8～3.25, 15.3～65.5 and 1208～7195 times as potent as 3-acetylaconitine, morphine and aspirin, respectively. The duration of analgesic effect of Bul assayed with pain stimuli of formaldehyde in mice was longer than that of morphine. No tolerance of analgesic effect was found after daily sc of Bul 0.15 mg/kg for 9 d in mice assayed with hot plate method. In nalorphine-challenge test, no jumping response was observed in mice treated with Bul 1.2 mg/kg, the maximal tolerance dose. Rats were given sc morphine 2.5 mg/kg bid for 120 d, withdrawal of morphine was followed by a decrease in body weight, which was used as a parameter of abstinence syndrome, Bul sc 0.1 mg/kg did not alter theoweight loss of morphine-treated rats. One male monkey developed physical dependence after se morphine of which the daily dose was increased progressively from 2.5 to 25 mg/kg in 21 d and then maintained for 120 d. Bul 30 μg/kg sc did not supress the withdrawal signs evoked by ip nalorphine 0.5 mg/kg. The results indicate that Bul induced no morphine-like tolerance nor physical dependence.The analgesic action of Bul was not antagonized by naloxone, but was eliminated by intraperitoneal injection of reserpine 3 mg/kg 3 h prior to Bul. The antagonistic action of reserpine to Bul could be reversed by icv 5-HT or ip 5-HTP given 3 h after reserpine. So, the analgesic effect of Bul may be related to the 5-HT level in brain.It was found that Bul exhibit strong local anesthetic activity when injected around the Sciatic erve in mice, the ED₅₀ concentration of Bul (50% mice with signs of sciaric nerve block) was 0.0029%.