The epidemic of deaths from bronchial asthma in New Zealand was investigated by a 2 yr national review of all deaths of persons under 70 yr where asthma appeared in part I of a death certificate or in a coroner''s report of cause of death. Information about the patients, the characteristics and management of their asthma, and the circumstances of the fatal episode was obtained by interviewing relatives and general practitioners and perusal of hospital records. The reviewing panel of the asthma task force of the Medical Research Council considered 271 of the 342 deaths studies were due to asthma. A high national asthma mortality rate (5.1/100,000) was confirmed, with rates for Maoris (18.9) and Pacific Islanders (9.4) considerably higher than that for Europeans (3.4/100,000). After standardizing for age and ethnic groups, there remained a 3-fold variation in mortality rates among health districts suggesting regional differences in prevalence, severity or management of asthma. No single cause for these high mortality rates was found. Of the deaths 1/4 occurred in patients who had previous life threatening attacks. Excessive use of bronchodilator drugs did not account for the high mortality rates, but inappropriate prolonged use of a home nebulizer may have delayed institution of other therapy in a few cases.