This is the first report of both reduced (RAA) and total (TAA) plasma ascorbic acid levels in women who smoke and are on oral contraception. 155 normal healthy subjects were investigated. A study questionnaire was completed including age, method of contraception, smoking status, and food intake at breakfast, prior to attending the clinic. Biochemical assays were promptly carried out without knowledge of subjects's clinical or dietary status. One-way analysis of variance revealed that oral contraception per se, barrier or IUD methods have no effect on plasma ascorbic acid levels. The mean values (mg/dl ± SD) for plasma RAA between smokers and nonsmokers were 0.512 ± 0.241 and 0.601 ± 0.263; and that for TAA were 0.565 ± 0.232 and 0.682 ± 0.231, respectively. Significant decreases in both plasma RAA (p < 0.05) and TAA levels (p < 0.001) were observed in smokers. Age was an interacting variable. No association of smoking or oral contraceptive use was seen with RAA or TAA levels among women less than 26 years, but decreases in both RAA and TAA levels were evident among smokers aged 26 years or older. The present study emphasizes that total exposure to smoking, e.g., pack years, is a significant confounding variable in the study of plasma ascorbic acid levels.