Objective To investigate the effects of the guanine nucleotide exchange factor C3G (Crk SH3-domain-binding guanine-nucleotide-releasing factor) overexpression on the survival of cardiomyocytes and the underlying mechanisms.Methods H9C2 cardiomyocytes were transiently transfected with pCXN2-Flag or pCXN2-Flag-hC3G (overexpressing human C3G mRNA) plasmids, and then were exposed to hypoxia/reoxygenation (H/R) treatment. The cardiomyocytes were divided into blank group, empty plasmid group, C3G overexpression group, blank+H/R group, empty plasmid+H/R group, and C3G overexpression+H/R group. The expression of C3G mRNA was detected by RT-PCR, and the expression of C3G and p-ERK1/2 protein was detected by Western blotting analysis. The apoptosis rates of cardiomyocytes were analyzed by flow cytometry in each group, and the cell proliferation rates were analyzed by MTT.Results C3G overexpression increased cell proliferation rate and expression of C3G mRNA and protein, p-ERK1 protein(all P<0.01), and decreased apoptosis rate (P<0.05,P<0.01) compared to the blank and empty plasmid groups; the same was true for C3G overexpression+H/R group when compared to the blank+H/R and empty plasmid+H/R groups. Expression of p-ERK2 protein in C3G overexpression+H/R group was increased compared to blank+H/R and empty plasmid+H/R groups (P<0.01).Conclusion C3G overexpression can promote cell survival in the cardiomyocytes, which might be mediated by the increase of p-ERK1/2 protein expression and apoptosis inhibition.