It is not possible to generalize how old a man is when he is infertile, as there is a wide range of clinically specific age differences. Generally after the age of 60, it is possible to be infertile, although there are some men who can be fertile after 60. In general, the function of the testes declines between the ages of 50 and 60, and some men gradually lose their fertility. Whether a man can have children depends on whether his sperm quality is normal or not. If the sperm quality is normal and there is no other disease in his body, he can still have children. Normally, men should develop good dietary and hygienic habits, exercise properly, go to bed early and get up early, eat a light diet, and if they feel unwell, they should go to regular hospitals for consultation and treatment.