Abstract
There is a widespread perception that the prevalence of asthma is increasing in many parts of the world. Increases in hospital admissions and general practice consultations for asthma have been reported, but such increases may reflect changes in the diagnosis and treatment of asthma rather than increases in the prevalence of the disease. Epidemiological surveys from several countries provide compelling evidence that the prevalence of asthma in children is increasing. The observation that the proportion of children who have other atopic diseases such as hay fever and eczema is also increasing suggests that the upward trend in asthma prevalence reflects a more general increase in atopy. To date, however, there is only limited evidence that the proportion of the general population sensitised to common allergens has increased.