Asthma mortality rates have been increasing since 1979, but rates of change among different demographic subgroups have not been examined in detail. This analysis identifies the demographic subgroups that are most responsible for the increase in asthma mortality rates in the United States between 1979 and 1996. The analysis is limited to those death certificates that specified asthma as the underlying cause of death. Blacks, females, and people aged 65 and older had the largest increases in age-adjusted asthma mortality rates between 1979 and 1996. When all three demographic variables are considered simultaneously, black females aged 65 years and older had the highest crude asthma mortality rates in 1996 and the largest increase in rates since 1979. However, white females aged 65 years and older contributed the most to the increase in age-adjusted rates between 1979 and 1996 because of their relatively larger population size. Overall, the increase in asthma mortality rates between 1979 and 1996 was due primarily to increased mortality rates in the population subgroup aged 65 years and older Even though the rapid increase in asthma mortality rates in those aged 65 years and older shows evidence of a slight reversal after 1989, efforts to develop strategies to reduce overall mortality from asthma should concentrate on middle-aged and elderly women.