Our study aimed to determine the effects of Losartan and PD123319 in ischemia/reperfusion (IR) injury in isolated perfused rat heart. The study used 40 male Wistar albino rats that were grouped as Control, IR, and IR groups which received Losartan (20 mg/kg), PD123319 (20 mg/kg) and Losartan+PD123319. The hearts were attached to Langendorff isolated heart system by employing in situ cannulation method, and cardiodynamic parameters were recorded during the experiment. At the end of experiment hearts were retained for biochemical analysis, and all data were statistically evaluated. A partial recovery of cardiodynamic parameters was observed in all treatment groups. A significant increase in oxidative stress parameters were seen in the IR group, whereas all treatment groups exhibited lower increase. Furthermore, levels of all antioxidant parameters were significantly lower in the IR group, but higher in the treatment groups. Effects on all parameters were much more remarkable in PD123319 group. Levels of angiotensin II and renin were increased (P<0.001) with IR application, and decreased (P<0.001) with the treatment of both antagonists. In conclusion, treatment of Losartan and PD123319 played a cardioprotective role against IR injury, PD123319 being more effective in this protection.