Patient understanding of the nature of asthma and of its management was assessed using an interviewer administered questionnaire in a community sample of asthmatics identified through prescriptions at randomly selected Dunedin city pharmacies. Of 135 subjects whose histories, and lung function data where available, were consistent with asthma, 20 did not know they had asthma. Only half could give a simple explanation of asthma, and many were confused about therapies, especially the use of corticosteroids. Only half demonstrated satisfactory aerosol inhalation technique. Deficiencies in medical management including lack of lung function monitoring, regular followup and provision of a crisis plan for severe attacks were noted. Patients previously hospitalised more often had a crisis plan and recalled advice on management of asthma, but had little knowledge about the nature of the condition. The continuing high asthma mortality rate in New Zealand may in part reflect management deficiencies both in long term care and in recognition and management of severe attacks. These may be compounded by poor patient understanding of asthma.