It has been suggested that lung function can be altered by both free radical and oxidant exposure, while antioxidant vitamin intake is positively related to lung function. However, the information on the relation of blood levels of oxidants and antioxidants to lung function is sparse. The present cross-sectional study, conducted from September 1995 to May 1996, analyzes the association between lung function measured as forced expiratory volume in 1 second (FEV1) with 1) levels of thiobarbituric acid-reactive substances in plasma (p-TBARS) and in low and very low density lipoprotein cholesterol (LDL cholesterol/VLDL cholesterol-TBARS) as indicators of lipid peroxidation and 2) compounds with antioxidant activity, erythrocytic glutathione, plasma glutathione peroxidase, trolox equivalent antioxidant capacity, and serum bilirubin, which may protect against lipid peroxidation. The analysis was carried out in 132 nonsmoking subjects aged 37-73 years who were randomly selected from the residents of Erie and Niagara counties, New York. FEV1 in percent of the predicted value (FEV1%) was negatively and statistical significantly associated with p-TBARS (r = -0.19). A negative association with borderline statistical significance was observed between FEV1% with low density lipoprotein cholesterol/very low density lipoprotein cholesterol-TBARS (r = -0.16) and glutathione (r = -0.16), while FEV1% was positively related to serum bilirubin (r = 0.15). Participants in the lowest quartile of FEV1% showed significantly higher levels of p-TBARS (p = 0.02) and lower levels of bilirubin (p = 0.04) than did those in the highest quartile. Our results suggest that increased lipid peroxidation is associated with pulmonary airway narrowing in the general population.