Three groups (n = 50 each) of pregnant smokers wanting to quit the habit were assigned to three different intervention programs around their 18th week in pregnancy. Group 1 participated in a smoking cessation program offering several self-help methods; group 2 attended a doctor's information meeting at the hospital; and group 3 received a pamphlet on the deleterious effects of smoking in pregnancy. For Group 4, the control group, there was no intervention. In all three intervention groups, more than one-third reduced their smoking to almost half, while 38% quit altogether in group 1, compared with less than 10% in groups 2 and 3. Twelve months later, 16%, 6% and 8% respectively, remained abstinent in the three groups. In groups 2 and 3, abstinence proved to be of the same magnitude as in the control group. We conclude that smoking in pregnancy, being one of the few amenable to risk factors affecting the perinatal death statistics, demands an active smoking cessation program during pregnancy led by specially trained health professionals.