The prevalance of opioid addiction is releativly high in Iran. Since the mechanism (s) of opioid addiction are not clear, this social problem still remains unresolved. In the present study, the effects of water-alcohol extract of Papaver rhoeas on the acquisition and expression of morphine withdrawal in morphine-dependent N-MARI mice (20-25 g) were investigated. The animals became dependent to morphine and the extract of the Papaver rhoeas was administered during and after induction of morphine dependence. Then, withdrawal syndroms were tested with naloxone (4 mg/kg) injection. Results showed that administration of naloxone after four days morphine treatment (12.5, 25 and 50 mg/kg), induced diarrhea and also increased the number of jumping in animals. The increase was significant for a dose of 50 mg/kg of morphine. On the other hand, administration of the plant extract (25, 50 and 100 mg/kg) did not induce any changes in the feaces or number of jumping behaviour in the animals. Injection of the same extract (25, 50 and 100 mg/kg) 30 min before morphine (50 mg/kg) administration, caused an increase in number of jumping but reduced the diarrhea in animals. Injection of the plant extract (25, 50 and 100 mg/kg) on the test day, 30 min before naloxone administration also decreased the number of jumping and diarrhea in morphine-dependent animals. It could be concluded that the extract of Papaver rhoeas can amilorates the withdrawal syndrom in morphine-dependent mice. Therefore, the extract might be useful for treatment of withdrawal signs in opioid addicts.