BACKGROUND: The anti-inflammatory effects of n-3 polyunsaturated fatty acids (n-3 PUFA) have been demonstrated both in vitro and in vivo. The results of epidemiological studies suggest that fish consumption has a beneficial effect on lung function and prevalence of asthma. However, data from intervention trials have not revealed a beneficial effect of n-3 PUFA supplementation in patients with established disease. OBJECTIVE: To study the effects of short-term n-3 PUFA supplementation in addition to maintenance therapy on exhaled nitric oxide in asthmatic patients. METHODS: A double-blind, placebo-controlled trial was undertaken in 20 women with asthma. Patients received either a combination of eicosapentaenoic acid and docosahexaenoic acid plus 10 mg vitamin E or placebo twice daily for 2 weeks. The primary outcome measure was the fraction of exhaled nitric oxide (FeNO) and the secondary outcomes were asthma control (score on theAsthma Control Questionnaire [ACQI) and lung function (forced expiratory volume in 1 second [FEV1]). RESULTS: No significant differences were observed in FeNO, ACQ score, or FEV1 between patients receiving n-3 PUFA supplementation and those receiving placebo. CONCLUSIONS: Short-term dietary supplementation with n-3 PUFA in women with stable asthma was not associated with statistically significant changes in FeNO, asthma control, or lung function.