The data presented show that elderly men have significantly lower plasma ascorbic acid concentrations than elderly women at similar intakes of ascorbic acid. We hypothesize that this difference is due to lower renal tubular reabsorption of ascorbic acid in elderly men. The finding that more than half of the healthy elderly men had plasma ascorbic acid levels less than 0.3 mg/dl with daily intakes of ascorbic acid in the range of 40 to 50 mg raises concern about the rationale of lowering the RDA for vitamin C from the current value of 60 mg to 40 mg for men and 30 mg for women. This recommendation is inconsistent with efforts to improve the health status of elderly Americans by assuring adequate intakes of all essential nutrients. Our data do not allow us to determine an optimal intake of ascorbic acid for the elderly. The possibility of increased health benefits associated with intakes that exceed the current RDA of 60 mg needs to be examined. We believe, however, that a prudent approach to both of these questions would be to recommend that elderly receive a daily ascorbic acid intake that would allow plasma concentration to be maintained at or near 1.0 mg/dl. The daily level of intake required to maintain this level would be approximately 125 mg and 75 mg in healthy elderly men and women respectively. These intakes would assure adequate body reserves of ascorbic acid.