AIM: To observe the protective effect of non-wounded ischemic preconditioning on ischemic/reperfusion injury in isolated rat hearts. METHODS: 25 male SD rats, weighting (250?30) g, were randomly divided into three groups: control group (C, n= 8), anoxia/reoxygenation group (A, n= 8) and non-wounded legs ischemic preconditioning group (N-WIP, n= 9).Hearts were isolated from rats and perfused on a Langendorff apparatus with a normal Krebs-Henseleit buffer (saturation 95% O 2+5% CO 2) at a constant pressure (8.33 kPa) and temperature (37 ℃) in C group ; Following 15 min equilibration, hearts were subjected to 15 min of global ischemia and 15 min reperfusion (37℃) in A group ; Rats were subjected to non-wounded leg repeated-brief ischemic preconditioning, and then treated in procedure similar to A group in N-WIP group.The activities of superoxide dismutase (SOD) and Ca 2+ -Mg 2+ -ATPase, malondialdehyde (MDA) content of efflux from coronary vessel and myocardium, myocardium monophasic action potential and contractile force were measured before ischemia, 15 minutes after ischemia and 5, 15 minutes after reperfusion. RESULTS: Compared with A group, non-wounded legs ischemic preconditioning reduced the incidence of reperfusion arrhythmias ( P