A final report in book form on "Epidemiology" describes the nineteen concerted actions carried out in this field during the fourth programme of medical and health research (1987-1991). The research areas covered by these actions are: - Cancer; - Age-related health problems; - Environment and life-style related health problems. The experience gained from epidemiological research within the programme, based exclusively on concerted actions, has produced real results: The creation of networks of research teams in Europe; the promotion of national financing of research projects relevant to European priorities in health research; harmonization of methodologies in Europe; the standardization of data collection and the setting up of European registers. The 370-page publication includes reports on each of the concerted actions and provides contact information. In addition, an appendix sets out guidelines on ethical issues in epidemiological research, containing the minimum common standards of practice recommended for use by project leaders and participants in the operation of future concerted actions.