Background: A reduced dietary intake of n-3 fatty acids, in association with increased n-6 fatty acid intake, has been proposed as a potential aetiological factor for chronic obstructive pulmonary disease (COPD) and asthma. However the relative importance of individual fatty acids within the n-3 and n-6 categories in this effect has not been widely investigated. We have studied the relation between individual fatty acid intakes, lung function, and self-reported respiratory symptoms and diagnoses in a representative sample of over 13,000 Dutch adults. Methods: Intake of individual fatty acids was estimated by a food frequency questionnaire and analysed in relation to measures of forced expiratory volume in one second (FEV1), and to questionnaire-reported wheeze, asthma, and COPD symptoms. Results: After adjusting for confounding we found no protective association between individual n-3 fatty acid intakes and FEV1. Higher intakes of some n-6 fatty acids were associated with lower FEV1, this effect being most marked for c22:4 n-6 docosatetraenoic acid (reduction in FEV1 between highest and lowest quintile of intake = 54.5 ml (95% CI -81.6 to -27.4)). Most of the n-6 fatty acid effects interacted significantly with smoking, their effects being strongest in current smokers. Individual n-3 fatty acid intakes were generally associated with a higher risk of wheeze in the past year, but otherwise there was little or no association between fatty acid intake and wheeze, doctor-diagnosed asthma or other respiratory symptoms. Conclusions: A high intake of n-3 fatty acids does not appear to protect against COPD or asthma, but high intake of several n-6 fatty acids is associated with a significant reduction in FEV1, particularly in smokers. These findings indicate that high dietary intake of n-6 fatty acids, rather than reduced n-3 intake, may have an adverse effect on lung health.