Four types of corticosteroid inhaler devices are available in New Zealand for first-line treatment of asthma, including two aerosol systems [Autohaler (3M Healthcare Ltd, Loughborough, U.K.; 3M Pharmaceuticals (Australia Pty Ltd, Sydney, Australia) and MDI (Glaxo Wellcome PLC, Ware, U.K.)] and two dry powder systems [Diskhaler (Glaxo Wellcome) and Turbuhaler (Astra AB, Sodertalje, Sweden)]. Rates of asthma-related health care consumption and treatment outcomes associated with use of the different inhalers are unknown. In this retrospective survey, asthma-related primary health care consultation and prescription patterns were compared in a large general practice population for each corticosteroid inhaler device prescribed as first-line treatment. An electronic search of a computerized clinical database yielded the medical records of 5704 patients with physician-diagnosed asthma who were prescribed either the Autohaler, Diskhaler, MDI or Turbuhaler as their sole corticosteroid inhaler device in the previous 12 months. The mean daily inhaled corticosteroid dose was lowest for the Autohaler (569 micrograms day-1; 95% CI: 538-605), followed by the Diskhlaer (638 micrograms day-1; 95% CI: 609-670) and MDI (665 micrograms day-1; 95% CI: 638-673), and was highest for the Turbuhaler (990 micrograms day-1; 95% CI: 954-1029, P