Previous studies have shown that due to differences in the progression of the smoking epidemic European countries differ in the direction and size of socioeconomic variations in smoking prevalence. We studied differences in the direction and size of inequalities in lung cancer mortality by the educational level of subjects in 10 European populations during the 1990's. We obtained longitudinal mortality data by cause of death, age, sex and educational level for 4 Northern European populations (England/Wales, Norway, Denmark, Finland), 3 continental European populations (Belgium, Switzerland, Austria), and 3 Southern European populations (Barcelona, Madrid, Turin). Age- and sex-specific mortality rates by educational level were calculated, as well as the age- and sex-specific mortality rate ratios. Patterns of educational inequalities in lung cancer mortality suggest that England/Wales, Norway, Denmark, Finland and Belgium are the farthest advanced in terms of the progression of the smoking epidemic: these populations have consistently higher lung cancer mortality rates among the less educated in all age-groups in men, including the oldest men, and in all age-groups in women up to those aged 60-69 years. Madrid appears to be less advanced, with less educated men in the oldest age-group and less educated women in all age-groups still benefiting from lower lung cancer mortality rates. Switzerland, Austria, Turin and Barcelona occupy intermediate positions. The lung cancer mortality data suggest that inequalities in smoking contribute substantially to the educational differences in total mortality among men in all populations, except Madrid. Among women, these contributions are probably substantial in the Northern European countries and in Belgium, but only small in Switzerland, Austria, Turin and Barcelona, and negative in Madrid. In many European countries, policies and interventions that reduce smoking in less educated groups should be one of the main priorities to tackle socioeconomic inequalities in mortality. In some countries, particularly in Southern Europe, it may not be too late to prevent women in less educated groups from taking up the smoking habit, thereby avoiding large inequalities in mortality in the future in these countries.