It has been reported that angiotensin Ⅱ(AⅡ) has antiopioid effect. However, the mechanism of this action is still not understood. To evaluate a possible interaction on c-fos protooncogene expression between A Ⅱ and DPDPE (δ receptor agonist) or NDAP (к receptor agonist) , the changing patterns of Fos protein in rat brain (less cortex and cerebellum) tissue induced by them were determined by immunoprecipitation. The results indicated that A Ⅱ at 0.1 μmo/L markedly evoked the Fos protein expression in brain tissue. Meanwhile, both DPDPE (0.1μmol/L) and NDAP (0.1μmol/L) could induce Fos protein increase in brain although their effects were less than that induced by AⅡ.The levels of Fos protein expression by AⅡ plus DPDPE or NDAP are lower than that induced by AⅡ individually. It is suggested that the action on c-fos expression between AⅡ and opioids is antagonistic. And opioids may weaken the evoked action of AⅡ on c-fos expression in the brain.