Objective: To study protective effect of insulin against cardiomyocyte apoptosis in anoxia/reoxygenation (A/R) injury of neonatal rat. Methods:The model of A/R injury was finished through receiving anoxia for 2 h and reoxygenation for 4 h in cultured cardiomyocytes of neonatal rat. The cardiomyocytes were divided randomly into 3 groups: control group (CON), anoxia/reoxygenation group (A/R) and insulin-treated group (INS). At the end of reoxygenation of 4 hours, activities of lactate dehydrogenase (LDH), contents of malondialdehyde (MDA) were assessed through spectrophotometric procedures, myocyte apoptosis were detected through TUNEL and DNA Ladder. Results: MDA, LDH, and Apoptosis Index were significantly decreased in INS group compared with A/R group (P<0.01). Conclusion: Insulin has a protective effect against A/R injury in cultured cardiomyocyte of neonatal rat; the protective mechanism may contribute to antiapoptosis of insulin. Objective: To study protective effect of insulin against cardiomyocyte apoptosis in anoxia / reoxygenation (A / R) injury of neonatal rat. Methods: The model of A / R injury was finished through receiving anoxia for 2 h and reoxygenation for 4 h in cultured cardiomyocytes of neonatal rat. The cardiomyocytes were divided into 3 groups: control group (CON), anoxia / reoxygenation group (A / R) and insulin-treated group (INS). At the end of reoxygenation of 4 hours, activities of lactate dehydrogenase (LDH), contents of malondialdehyde (MDA) were assessed by spectrophotometric procedures, myocyte apoptosis were detected by TUNEL and DNA Ladder. Results: MDA, LDH, and Apoptosis Index were significantly decreased in INS group compared with A / R group 0.01). Conclusion: Insulin has a protective effect against A / R injury in cultured cardiomyocyte of neonatal rat; the protective mechanism may contribute to antiapoptosis of insulin.