The circumstances surrounding 38 deaths from asthma in hospital in New Zealanders under 70 years of age between August 1981 and July 1983 have been analysed. Twelve deaths did not appear to be preventable, all but one occurring in chronic severe asthmatics despite apparently optimal therapy. Critical delays by patients or relatives in seeking medical help occurred in six cases, and inadequate assessment of severity and undertreatment by medical practitioners prior to the patient reaching hospital was a major contributing factor in a further six deaths. In four cases, insufficient speed and indecisive treatment in the accident and emergency department appeared to contribute to death. Ten patients died after many hours or days in hospital wards in circumstances where assessment, monitoring and treatment were deficient. There were no deaths in intensive care units. Urgent expert assessment is necessary in A & E departments, and more severe cases should be managed in intensive care units. Patients with acute severe asthma may need continuous oxygen, intravenous therapy and close objective assessment for a week or more after hospitalisation.