Ann Woolcock's studies of airway function in asthma have resulted in a widely used method for demonstrating disease in the small airways and for identifying subjects at risk of severe and potentially fatal asthmatic attacks. She has introduced new epidemiological methods for international studies of asthma, has identified the house dust mite as an important allergen and was the first to describe changes in peptidergic nerves in asthma. She has introduced new therapeutic plans for the management of the disease internationally. She has also made important contributions to the understanding of racial differences in lung function and of the effects of smoking.