Between 1981 and 1984, 10,923 male and 624 female employees of the Australian petroleum industry were interviewed and the information that was collected included a detailed life-time smoking history. Comparison with another survey suggested that, in terms of smoking habits at least, this industrial population did not differ substantially from the general population. On the assumption that reasons for entering and leaving the industry are unconnected with smoking habit, the data were analysed by birth cohorts. In men, each successive generation has contained fewer smokers at every age over 20 years and this is due both to a reduction in the rate of starting to smoke, and to an increase in the cessation rates. In the case of women, the situation is reversed, and successive generations show an increasing prevalence and increasing starting rates.