This present study, conducted in 1991, examined trends in the prevalence, severity and medical management of asthma in European school children by repeating the protocol of a study performed in 1985, using the same schools and questionnaire. One thousand, nine hundred and one children in 1991 were compared with 1084 children in 1985. The prevalence of respiratory symptoms increased significantly by approximately one-third, although the increase in the diagnostic label 'asthma' did not increase significantly. Asthma severity indices (> 12 asthma attacks in the last 12 months and symptoms in the last month) were not significantly increased, except for night cough in the last month (1985 7.0%, 1991 9.9%, P = 0.008). In 1991, children with wheeze in the last 12 months were more likely to be diagnosed as having asthma and treated with bronchodilators and prophylactic drugs than in 1985. We conclude that the prevalence of asthma symptoms has increased from 1985 to 1991, but the two indices of severity of asthma are mostly unchanged. Diagnosis of asthma in children with symptoms has improved but asthma still appears underrecognized. Drug treatment of asthma has increased.