Objective To detect the expression of caspase-3 in the cochlea of old aged guinea pigs.Methods Guinea pigs of the experimental group were 33 to 35 months old,and those of the control group were 2 to 3 months old.Caspase-3 was detected in the cochlea of both groups with the method of immunohistochemistry.Results The expression of caspase-3 was positive in the cochlea of experimental guinea pigs,and the caspase-3 positive area was in spiral ganglion cells,while caspase-3 was negative in the control group.Conclusion The expression of caspase-3 was positive in the spiral ganglion cellsof aged guinea pig,which suggests that caspase-3 plays a very important part in the process of aging of the guinea pig's cochlea.