Health impact assessments (HIA) dominantly apply only qualitative evaluation, although a comprehensive HIA ideally integrates both qualitative and quantitative evidence and methods, since quantification has several advantages when using assessment results in the decision making process. In the frame of the Risk Assessment from Policy to Impact Dimension EU project, quantitative assessment of several health outcomes has been integrated in the HIA of the recently prepared anti-smoking policy of Hungary, which had the primary goal of protecting non-smokers from environmental tobacco smoke exposure that is proved to be an effective measure for the reduction of smoking related morbidity and mortality that pose critically high burden on the Hungarian population. A comprehensive, prospective HIA was carried out on the proposed amendment of Act No XLII of 1999 on the protection of non-smokers to introduce smoking ban in closed public places, workplaces and public transport vehicles. Full chain approach was used to identify basic rules for prioritizing the major impact pathways with special attention to the feasibility of quantifying exposure and outcome. Exposure assessment relied on international experiences, while outcome assessment calculated measures of disease burden, like attributable death and disability adjusted life years, for a baseline and a predicted situation after the proposed changes take place. The major impact of the proposal was identified to decreases prevalence of active and passive smoking resulting in considerable positive effect on several diseases, most importantly lung cancer, chronic pulmonary diseases, coronary heart diseases and stroke. For these diseases, health outcomes could be quantified as close to 1700 lives and 22000 life years saved annually in total in the 10 million population of Hungary. As demonstrated by the results, providing smoke-free public places has an unambiguous positive impact on the health of the public that has been confirmed by the quantified health gain. The demonstrated methodology offers a practicable example for applying quantitative risk assessment integrated in health impact assessments.