Objective To observe the change of renal function and cell apoptosis after injecting SB203580 before and after reperfusion, and investigate the protective role of p38 MAPK inhibitor SB203580 for ischemic/reperfused kidney in rats. Methods p38 MAPK inhibitor SB203580 was injected by tail vein into rats with ischemic kidney before and after reperfusion. The plasma levels of creatine and BUN were measured at various time points. The apoptotic rate in the renal tissue at various time points was determined using TUNEL. Results Administering SB203580 before reperfusion could decrease renal cell apoptotic rate, and renal function damage. Administering SB203580 after reperfusion had not obvious effect on the renal function and cell apoptosis. Conclusion Administering p38 MAPK inhibitor before reperfusion can attenuate post-ischemic renal fuction damage and cell apoptosis.