Abstract： Objective To investigate (1) whether ischemic preconditioning (IPC) could protect immature rabbit hearts against ischemia-reperfusion injury and (2) the role of KATP channel in the mechanism of myocardial protection. Since cardioplegia is a t raditional and effective cardioprotective measure in clinic, our study is also d esigned to probe the compatibility between IPC and cardioplegia.Results The recovery of CF, HR, LVDP and ±dp/dtmax in preconditioned hearts was b est am ong the four groups. The incidence of arrhythmia was low and less CK-MB leaked out in the IPC group. Myocardial ATP content was better preserved by IPC. Pre treatment with glibenclamide completely abolished the myocardial protection prov ided by IPC, but did not affect ischemia-reperfusion injury.Conclusions While applying cardioplegia, IPC provides significant cardioprotective effects. Activation of KATP channels is involved in the mechanism of IPC-produced cardioprotection.