SASAKI, R., KUROKAWA, T., KOBAYASI, T. and TERO-KUBOTA, S. Influences of Sex and Age on Serum Ascorbic Acid. Tohoku J. exp. Med., 1983, 140 (1), 97-104-The concentrations of total ascorbic acid, reduced and oxidized forms of ascorbic acid, the ESR intensity of ascorbate radical, and the ratio of oxidized form of ascorbic acid to total ascorbic acid (DAsA/AsA) were estimated on 217 healthy controls, whose ages ranged from 12 to 96 years, in order to examine influences of sex and age. The concentration of total ascorbic acid was higher in females than in males throughout all age classes, but the oxidized form did not show a sex difference. Then it was found that the reduced form was higher in females than in males throughout all age classes. The concentrations of total ascorbic acid and reduced and oxidized forms of ascorbic acid, and the ESR intensity declined with age, but the DAsA/AsA ratio increased with age.