We have reinvestigated 92/101 children aged 10, who before the age of 2 years were admitted to a paediatric ward due to wheezing bronchitis. At the present time, 70% are symptom-free without medication, 20% have mild asthma, 8% moderate and 2% severe asthma. Persistent asthma correlated significantly to the presence of some other atopic disease in recent years, to early start of wheezing during infancy and to intense obstructive disease as a young child, while initial respiratory syncytial virus infection did not. A clear-cut relationship between smoking in the home in infancy and persistent asthma emerged (not visible at a preschool follow-up). The histamine challenge results correlated to the clinical picture. A normal histamine challenge was seen in 63%, mild hyperresponsiveness in 19%, moderate in 12% and pronounced hyperresponsiveness in 6%. The figures for persistent asthma and bronchial hyperresponsiveness are high compared with the prevalence of asthma in the overall population of schoolchildren.