The aim of the present study was to examine the influence of childhood respiratory infections on adult respiratory health. In 1992-1994, the European Community Respiratory Health Survey recruited community based samples of 20-44-yr-old people from 48 centres in 22 countries. Study participants completed questionnaires and underwent lung function testing. On average, 8.9 yrs later, 29 centres re-investigated their samples using similar methods. Mixed effects models comprising an estimate for the random variation between centres were used to evaluate the relevant associations. In total, 9,175 patients participated in both studies, of whom 10.9% reported serious respiratory infections (SRI) before 5 yrs of age and 2.8% reported hospitalisation for lung disease (HLD) before 2 yrs if age. SRI was associated with current wheeze (odds ratio (OR) 1.9, 95% confidence interval (CI) 1.7-2.2), asthma (OR 2.5, 95% CI 2.2-3.1), and lower forced expiratory volume in one second (FEV(1); 89 mL; 95% CI 54-126), forced vital capacity (FVC; 49 mL; 95% CI 8-90) and FEV(1)/FVC ratio (-1.2%; 95% CI -1.8- -0.6). Childhood respiratory infections were also associated with new asthma (OR 1.5, 95% CI 1.03-2.0), new wheeze (OR 1.5, 95% CI 1.0-2.4) and persistent wheeze (OR 2.2, 95% CI 1.4-3.6) but not with a decline in lung function. Similar findings were observed for HDL. These associations were significantly consistent across centres. SRI was associated with lower FEV(1) when excluding ever asthmatics and current wheezers. The impact of early infections was significantly larger in subjects exposed to maternal or active smoking. The impact of childhood respiratory infections on the respiratory system may not only last into adulthood but also influence development and persistence of adult respiratory morbidity.