The aim of this project was to evaluate the effect of intensive individual anti-smoking counselling among pregnant women from a Polish urban community with a large representation of socially underprivileged women. The study was conducted between 1 December 2000 and 31 December 2001. Out of 204 women who were asked to take part in a midwives-assisted program of educational counselling to stop smoking, 152 (74.5%) agreed to participate. The intervention program included four visits of a midwife trained in smoking cessation techniques to the home of a smoking pregnant woman. The control group were 145 pregnant women who on the first visit to a maternity unit received only a standard written information on the health risk from maternal smoking to the foetus. The percentage of pregnant women who quitted smoking during the project was 46.1% in the intervention group and 23.4% among the controls (p < 0.001). After combining the intervention group with the women who refused to participate in the project, the rate of quitting was 36.3%, still significantly higher than in controls (p = 0.01). The strongest influence of the intervention was found among women smoking more than 5 cigarettes/day. Women covered by the intervention programme, who reported smoking in previous pregnancies, were found to quit smoking to a much higher extent than the controls with a similar background. Such pattern was also observed for women whose husbands were smokers. The benefits of the intervention, especially for the socially underprivileged women, seem to result from an increased proportion of subjects who undertook a quitting attempt, rather than the effectiveness of these attempts. In the intervention group, among the subjects who did not manage to quit smoking during pregnancy, the number of women who at least slightly reduced their smoking rate was twice as high as in the controls.