This study was aimed to investigate the effects of postconditioning by natural honey on reperfusion-induced cardiac arrhythmias in isolated rat heart. The isolated hearts were divided into four groups (1 control and 3 test groups) then mounted on a Langendorff apparatus at constant pressure. In the control group, the hearts wereperfused by a modified Krebs-Henseleit (K/H) solution during 30 min regional ischemia followed by 30 min reperfusion, however in the test postconditioning groups they were perfused with natural honey (0.25, 0.5 and 1%) enriched K/H solution from 10 min before to 10 min after reperfusion. The ECGs were analyzed to determine cardiac arrhythmias including the total number of ventricular ectopic beats (VEBs), number of ventricular tachycardia (VT), incidence and duration of VT and ventricular fibrillation (VF). Perfusion of isolated hearts with natural honey (0.25, 0.5 and 1%) produced significant reduction in the total number of VEBs (p<0.05 for all). In addition, honey (0.5 and 1%) significantly decreased the number and duration of VT (p<0.01 and p<0.05, respectively). The time spent in VF was lowered by perfusion of honey (0.25 and 0.5%) compared to the control group (p<0.05). For the first time, results of this study showed protective effects of postconditioning by natural honey on reperfusion-induced cardiac arrhythmias. Probably, antioxidant activity of honey, scavenging of free radicals and the presence of important energy sources such as glucose and fructose may involve in these protective effects.