Background: Although the quantification of health outcomes in a health impact assessment (HIA) is scarce in practice, it is preferred by policymakers, as it assists various aspects of the decision-making process. This article provides an example of integrating a quantitative risk appraisal in an HIA performed for the recently adopted Hungarian anti-smoking policy which introduced a smoking ban in closed public places, workplaces and public transport vehicles, and is one of the most effective measures to decrease smoking-related ill health. Methods: A comprehensive, prospective HIA was conducted to map the full impact chain of the proposal. Causal pathways were prioritized in a transparent process with special attention given to those pathways for which measures of disease burden could be calculated for the baseline and predicted future scenarios. Results: The proposal was found to decrease the prevalence of active and passive smoking and result in a considerably positive effect on several diseases, among which lung cancer, chronic pulmonary diseases, coronary heart diseases and stroke have the greatest importance. The health gain calculated for the quantifiable health outcomes is close to 1700 deaths postponed and 16 000 life years saved annually in Hungary. Conclusion: The provision of smoke-free public places has an unambiguously positive impact on the health of the public, especially in a country with a high burden of smoking-related diseases. The study described offers a practical example of applying quantification in an HIA, thereby promoting its incorporation into political decision making.