Six hundred and ten former and present pupils of the Asthma School in Odense (aged 6-18 years) have been questioned about knowledge and health behaviour in connection with their asthma. It was found that knowledge about the disease was quite insufficient prior to starting at the school; whereas behaviour and medication was more appropriate. A month later the level of knowledge about asthma had increased dramatically. Behaviour and medication had improved, too. At a follow-up one year after starting at the Asthma School it was found that the level of knowledge and positive behaviour had deteriorated a little; but it was still much better than it had been at the start. It appears that the Asthma School had a very positive influence on the health of the pupils. During the year after starting Asthma School the pupils had fewer days away from school, saw the GP less frequently and were hospitalized fewer times. All three changes were highly significant.