Objectives: To critically use data from experimental and observational studies to evaluate the public health impact of selected adverse drug reactions. To design and to carry out an analysis of the impact of adverse effects at a community level. To analyse the economic impact of adverse drug reactions on public health. Topics covered: Data generalization: from particular cases to population impact-1. The interpretation of the results of clinical trials and meta-analyses from the public health point of view Data generalization: from particular cases to population impact-2. Examples of the value of observational studies and meta-analyses of observational studies in the evaluation of the public health impact of medicines use. Public health impact - Case: Hormone replacement therapy Public health impact beyond case-control studies The importance of the denominator: case-population studies. The future of pharmacovigilance.