Epidemiologic data relating total circulating immunoglobulin E (IgE), an objective marker of allergy, to cross-sectional and longitudinal FEV1 as well as to methacholine bronchial hyperresponsiveness were obtained from 310 French adult men surveyed five years apart. Skin prick test responses to common aeroallergens, IgE level, and bronchial hyperresponsiveness were assessed at the end of the follow-up. IgE level was not associated with PD20 to methacholine. Cross-sectionally, age and height-adjusted FEV1 score was inversely related to total IgE level (regression coefficient of FEV1 score on Log[IgE] beta = -.20; p = 0.02). Stratified analysis showed that IgE level was associated with FEV1 score only in nonsmokers (beta = -0.52; p less than 0.001), an association that remained after exclusion of asthmatics. Longitudinally, five-year FEV1 decline was related to IgE in nonsmokers (regression coefficient of FEV1 decline on Log[IgE] beta = 19.9; p = 0.03) and exsmokers (beta = 18.9; p = 0.06) but not in current smokers. The relationship persisted, even if with lesser significance, among exsmokers after exclusion of asthmatics (beta = 17.2) and further exclusion of skin prick test-positive men (beta = 18.8). Whether IgE production also reflects factors other than allergy, possibly nonallergic inflammation, needs further investigations.