This report is based on previous data that showed that Turkish hamsters that hibernated lived longer than nonhibernating controls. Fluorescent microscopy was used to measure the lipofuscin content of brain and heart of hamsters that hibernated for various fractions of their lives. According to regression data the 13 animals that hibernated 11 to 37% of their lives had a slower accumulation of lipofuscin than 11 animals that hibernated 0 to 7% of their lives. It was calculated that the total amount of pigment accumulated during a life span was the same in both groups, in spite of the longer life of the hibernators.