There is limited knowledge concerning the energy turnover and energy requirements of the elderly. The aim of this study was to measure resting metabolic rate (RMR) and total energy expenditure (TEE), and to define activity energy expenditure (AEE) and physical activity level (PAL) in 11 78-year-old individuals. A further aim was to compare these measures with the same measures taken from the 11 subjects at age 73 years. Total body water (TBW) averaged 30.8 kg (SD 3.2) at age 73 and 28.8 kg (SD 3.5) at age 78 years (p<0.01). RMR was measured with a ventilated-hood system and averaged 5.60 MJ/day (SD 0.66) at age 73 and 4.77 MJ/day (SD 0.32) at 78 years (p<0.001). TEE, measured using the doubly labeled water method, averaged 9.64 MJ/day (SD 1.10) at age 73 and 8.30 MJ/day (SD 1.45) at 78 years (p<0.05). AEE averaged 4.04 MJ/day (SD 0.44) at age 73 and 3.53 MJ/day (1.13) at 78 years (ns). PAL averaged 1.74 at both ages. TBW, TEE, and RMR decreased, whereas AEE and PAL did not change substantially during the 5-year follow-up. The PAL values indicated a physically active lifestyle for the age group.