A study of respiratory symptoms and lung function in the elderly was performed in 1987 on an age-, gender- and symptom-stratified randomly selected sample of the general population over age 65 in the Southampton area. The present study aimed to follow-up this elderly population to examine the longitudinal rate of decline in lung function over 4 years, and the risk factors for increasing decline. In a cross-sectional study, these, and additional randomly selected subjects were examined to investigate (i) the cross-sectional relationship between serum IgE and lung function, (ii) the relationship between nutritional factors and both lung function and (iii) respiratory muscle strength. Longitudinally, smoking habits at the start of the study did not correlate with annual rate of FEV₁ decline. However, raised serum IgE, positive skin prick tests and increased bronchial responsiveness were all independently significantly associated with increased decline in lung function. However, after adjustment for all other co-variables, only the effect of increased methacholine responsiveness remained significant. On cross-sectional analysis, current smoking and IgE > 80 IU/ml were both significant predictors of an impaired FEV₁/FVC ratio. Together the effects were synergistic. Current smoking was also shown to be a significant risk factor for a serum IgE > 80 IU/ml. The mechanism for this is unclear. Smokers with elevated IgE levels did not have an increased prevalence of allergen specific IgE for any of 35 common allergens assessed by MAST-CLA. Cross-sectional analysis further showed that anthropometric measures did not correlate with spirometric measures. However, dietary intake, in particular vitamin E (but not vitamin C) consumption, as assessed by a food-frequency questionnaire correlated significantly with impaired FEV₁ and FVC. In conclusion, both lung function and respiratory muscle strength decline with age. Males have higher levels of each than females. Allergy and bronchial responsiveness are associated with an increased rate of decline in lung function, but the mechanisms of this relationship remains unclear.