Survival after lung transplantation is limited by bronchiolitis obliterans syndrome (BOS). Oxidative stress (OxS) can be associated with BOS due to chronic inflammation. The type of fat and antioxidant intakes may also contribute to OxS. Our aim was to compare OxS and nutritional intakes in non-BOS versus various stages of BOS. Fifty-eight lung recipients with versus without BOS were prospectively classified as: non-BOS; BOS Op-1 (mild), and BOS 2-3 (severe). We measured nutritional intake and plasma vitamins A, C, and E. Among a subgroup of 37 patients, OxS was assessed by measuring lipid peroxidation (LPO micromol/L MDA) and oxidized glutathione (GSSG) in bronchoalveolar lavage BAL fluid (BALF). One-way analysis of variance was used to compare groups. Results are reported as mean values +/- standard errors of the mean. There was no significant difference in demographic features on time posttransplant among groups. Although there were comparable cell counts in BALF, severe BOS patients showed significantly higher BALF LPO concentrations when compared with milder stage of BOS or with non-BOS (P = .001, for both). Severe BOS recipients also displayed higher BALF GSSG concentrations compared to milder stage of BOS (P = .001) or non-BOS (P = .007). In conclusion, patients with severe BOS were more oxidatively stressed compared with mild and non-BOS recipients.