The accumulation of lipofuscin, an important phenomenon during aging, suggests that the sexual maturity (puberty) of mammals is a starting point of the aging process. The rate of cardiac lipofuscin accumulation was not correlated linearly with maximum life span of mammals, but the correlation was a power function of the maximum life span. The rate of lipofuscin accumulation statistically correlated with the specific metabolic rate, and inversely correlated with the brain weight of mammals. The first appearance of lipofuscin showed a good correlation with the brain weight. However, the slope of the line was different between primates and domestic and laboratory animals. From these results, it is suggested that the accumulation of cardiac lipofuscin is dependent on the specific metabolic rate of mammals.