Earlier, we have shown that C-phycocyanin (PC), an antioxidant biliprotein pigment of Spirulina platensis (a blue-green alga), effectively inhibited doxorubicin-induced oxidative stress and apoptosis in cardiomyocytes. Here, we investigated the cardioprotective effect of PC against ischemia-reperfusion (I/R)-induced myocardial injury in an isolated perfused Langendorff heart model. Rat hearts were subjected to 30 min of global ischemia at 37°C followed by 45 min of reperfusion. Hearts were perfused with PC (10 µM) or Spirulina preparation (SP, 50 mg/l) for 15 min before the onset of ischemia and continued throughout reperfusion period. Untreated (control) hearts, at the end of 45 min of reperfusion, showed a significant decrease in the recovery of coronary flow (44%), left-ventricular-developed pressure (21%) and rate-pressure product (24%), increased release of lactate dehydrogenase (LDH) and creatine kinase (CK) in the coronary effluent, significant myocardial infarction (44%, of risk area), and TUNEL-positive apoptotic cells as compared to the pre-ischemic state. Treatment with PC or SP significantly enhanced the recovery of heart function and decreased the infarct size, attenuated LDH and CK release, and suppressed I/R-induced free radical generation. PC treatment reverted back the I/R-induced activation of p38 MAPK, Bax, and caspase-3, suppression of Bcl-2, and increase in TUNEL-positive apoptotic cells. However, I/R also induced the activation of ERK1/2 that was enhanced by PC treatment. Overall, these results for the first time showed that PC attenuated the I/R-induced cardiac dysfunction through its antioxidant and anti-apoptotic actions and modulation of p38 MAPK and ERK1/2.