Basal metabolism tests on 8 women and 14 men aged 74-106 yrs. showed calories per sq. m. body surface to be more constant than total calories or calories per kgm. body weight. Av. heat production was: 1 woman, aged 106 yrs., 21.1 cal./hr./sq.m.; 6 women, av. age 82.5 yrs., 27.4 cal./hr./sq.m.; and 14 men, av. age 81.6 yrs., 30.1 cal./hr./sq. m. No indication of a relationship between degree of senility and metabolic rate was found, but tidal air decreased as senility increased. The experimental results agreed better with the Harris-Benedict than with the Aub-DuBois, or Dreyer standards.