AIM: The present study was designed to determine whether Sini decoction (SND), a traditional Chinese medicine, induces delayed preconditioning-like effect in rat heart and the possible mechanism by which ischemia myocardium is protected. METHODS: Sprage-Dawleyt rats underwent three 5 min episodes of preconditioning ischemia 24 h prior to the global ischemia and reperfusion in ischemic preconditioning/second window of protection (IPC/SWOP) group or were pretreated with Sini decoction (5 mL?kg -1 ?d -1 for 3 days, the last treatment 24 h before global ischemia and reperfusion) in SND group. Myocardial infarct size, CK, LDH and NO were examined. p38 MAPK and PKC were determined by immunohistochemisty. RESULTS: Myocardial infarct size was significantly decreased, CK and LDH were decreased in the serum, NO 2 -/NO 3 - was increased in myocardial tissue in SND group as well as in IPC/SWOP group (there was no difference between the two groups). The expression of p38 MAPK and PKC were upregulated in myocardial tissue in SND and IPC/SWOP groups. CONCLUSION: These results suggest that Sini decoction induces delayed preconditioning-like effect in the rat heart, possibly via inducing p38 MAPK activation.