Asthma mortality in the age group 5-44 years appeared to be stable in Scotland in both males and females at a rate of approximately 1.0 per 100,000 during the period 1970-1988 despite an increase in the hospital discharge rate for asthma of approximately 4% per annum during that period. Two-thirds of these deaths occurred outside hospital. There was evidence of a seasonal variation in asthma deaths with a peak mortality occurring in August, four to six weeks after the peak in total pollen counts. Monthly variation in atmospheric pollution did not appear to account for the variation in asthma mortality. It is suggested that the seasonal variation in asthma mortality provides a basis for further studies to elucidate the factors contributing to these deaths.