We tested the hypothesis that ischemic postconditioning (IPost) induces autophagy and the activation of autophagy contributes to the cardioprotective effects against ischemia/reperfusion injury in rat hearts. Rats were subjected to IPost established by 3 cycles of 10-second reperfusion followed by 10-second ischemia at the end of 30-minute ischemia. The activation of autophagy was assessed by the morphological and biochemical examinations after 120-minute reperfusion in ventricular tissue. To investigate the contribution of autophagy to IPost, the rats were pretreated with the autophagy inhibitor 3-methyl-adenine (3-MA). We found that IPost increased the formation of autophagic vacuoles, the autophagic-related protein levels of LC3-II, Beclin1, lysosome-associated membrane protein 2, and cathepsin D, and the mRNA level of LC3 and Beclin1 in the risk zone of the postconditioned hearts. Furthermore, 3-MA treatment significantly reversed the reduction effect of IPost on infarct volume, and in the meantime, inhibited the induction of LC3 and Beclin1. In addition, 3-MA treatment inhibited the antiapoptotic-related protein levels of Bcl-2 and increased the apoptotic-related protein levels of Bad. Taken together, these results indicate that the protective effects of IPost are associated with the activation of autophagy in rat hearts.