Objective: To evaluate the effects of Zhumeria majdae essential oil (ZMEO) on morphine dependence and tolerance in mice.Methods: ZMEO (10,20,and 40 mg/kg) and clonidine (0.1 mg/kg) as the positive control were injected intraperitoneally (i.p.).The effect of ZMEO and clonidine on the dependence were evaluated by counting the number of jumps induced by naloxone (5 mg/kg) while the tolerance was evaluated by the tail-flick test.Results: ZMEO at the dose of 10 mg/kg during the development period led to a significant inhibition of morphine tolerance (P＜0.01),while it led to reduced morphine dependence with the doses of 20 and 40 mg/kg.ZMEO at two dose levels of 20 and 40 mg/kg indicated significant antinociceptive activity (P＜0.01),and significantly reduced the withdrawal signs (number of jumps) of mice (P＜0.01).Conclusions: ZMEO had significant effects on morphine tolerance and dependence.The linalool rich essential oil of Z.majdae plays a major role in the reduction of tolerance and dependence induced by morphine.