Both opiates and dopamine play important roles in learning and memory. Althoughsynergistic action between these two neurotransmitters has been found, their func-tional roles remain unclear. Here, low dose morphine (2.5 mg/kg) and low dose dopa-mine  receptor  agonists  (apomorphine  0.05 mg/kg;  SKF38393  0.01 mg/kg;bromocriptine 0.05 mg/kg), which have no effects on spatial recognition memory,were injected intraperitoneally into mice 30 minutes before a memory test in a two-trial recognition Y- maze. The Y- maze is based on the innate tendency of rodents toexplore novel environments and is therefore suitable for exploring the effects of mor-phine on learning and memory. Our results showed that both D1- like and D2- like do-pamine receptor agonists dose- dependently impaired the retrieval of spatialrecognition memory in the Y- maze, and co- administration of memory ineffectivedoses of apomorphine (0.05 mg/kg), SKF38393 (0.01 mg/kg), or bromocriptine(0.05 mg/kg) and of morphine (2.5 mg/kg) resulted in impaired spatial recognitionmemory retrieval in mice. These findings suggest the existence of interactions be-tween morphine and dopamine receptor agonists in memory processing and that acti-vation of the dopamine system might contribute to morphine- induced impairment ofmemory, which could provide insight into human addiction.