AIM: To observe the effect of crocetin on the apoptosis and the changes of its related regulating proteins caspase-3 and Bcl-2 expression induced by hydrogen peroxide (H_2O_2) in cultured cardiomyocytes. METHODS: Changes of cellular morphology were detected under microscope. Apoptosis rates of the cells were analyzed by PI staining with flow cytometry. Expressions of caspase-3 and Bcl-2 proteins in the cells were determined by immunofluorescence with flow cytometry. RESULTS: In the concentrations used, more severe morphological changes with higher apoptosis rate of the cultured myocardial cells were seen in each H_2O_2 group than that in control group. When treated with 1×10 -4 mol·L -1 H_2O_2, the caspase-3 was increased and Bcl-2 protein decreased remarkably in the cells. But each dosage of crocetin, especially the highest one (5×10 -5 mol·L -1, P<0.05 compared with 5×10 -7 mol·L -1 group), seemed efficient in maintaining the cell morphology, reducing the cell apoptosis rate and improving the changes in caspase-3 and Bcl-2 protein expression in the cells exposed to 1×10 -4 mol·L -1 H_2O_2. CONCLUSION: Crocetin obviously inhibits the apoptosis induced by H_2O_2 in the cultured myocardial cells. The mechanisms may involve the balance of the functions of the apoptosis-related regulating proteins, caspase-3 and Bcl-2 protein.