Lung cancer data were examined to determine whether the mortality rates of young Australian women have continued to increase in line with the proportions of them who have smoked tobacco. Trends in annual age-specific lung cancer mortality were estimated for 1965-1998. Age-specific mortality rates and age-adjusted ratios of mortality rates were calculated for birth cohorts. Proportions of smokers in those cohorts were estimated from results of eight national surveys of smoking, and their mean ages of commencement and years of smoking were assessed from surveys of smokers in two states. Lung cancer mortality rates of 20-44-year-old Australian women peaked in 1986. Age-adjusted mortality rates are lower for women born in the 1950s and 1960s than for women born in the 1940s, despite higher proportions of smokers, younger age of commencement and longer duration of smoking by age 30 years in the more recent cohorts. Increased smoking has not resulted in higher lung cancer mortality for Australian women born in the 1950s and 1960s. Reductions in tar yields of Australian-made cigarettes, which would have affected primarily those born after the 1940s, may be responsible.