The time course of radioactivity in plasma and urine after oral administration of a single dose of (1-14 C) ascorbic acid has been followed in healthy male volunteers smoking more than 20 cigarettes per day. The investigation was carried out under steady state conditions with regard to ascorbic acid plasma levels at intakes of about 30 to 180 mg/day. Smokers had a higher metabolic turnover than that found for nonsmokers. It was concluded, as a consequence, that a daily intake of at least 140 mg is required for smokers to reach steady state concentrations and total body pools comparable to nonsmokers for whom a daily intake of about 100 mg was previously reported to be appropriate.