Abstract. Introduction: Oxytocin (OT) was revisited recently as a hormone of cardiovascular system with several new functions in cardiovascular regulation. But less is known about its role in acute myocardial injury (MI). Aim of the study: was to investigate the possible protective effect of OT on the biochemical, histological and immunohistochemical changes of MI induced by isoprenaline (ISO) in adult male albino rats and studying the possible role of nitric oxide (NO) in its action. Materials and methods: Forty male albino rats were divided into 5 groups: control rats (Group I), acute MI rats (Group II), rats pretreated with OT prior to induction of MI (Group III), rats injected with a combination of OT and atosiban (ATO, OT receptor antagonist) prior to induction of MI (Group IV). In Group V, a combination of OT and nitric oxide synthase inhibitor (L-NAME) were injected to the rats prior to induction of MI. Results: OT produced a significant reduction in CPK, LDH, TNF- α, MDA, MPO and caspase-3 with significant increase in GSH-Px and NO. It also produces improvement in ECG. Blockade of OT receptor by ATO abolished the cardioprotective effect of OT. As well as a combination of OT and L-NAME decrease the cardioprotective effect of OT. While The histological and immunohistochemical study support these results as OT produced a significant reduction in apoptosis. So, OT has a protective effect against ISO-induced MI and NO is one of its mediators of action. Conclusion: We concluded that OT has antioxidant, anti-inflammatory and anti-apoptotic effects on MI and its effects were mediated through NO.