The authors review the various aspects of the MONICA project (Monitoring of Trends and Determinants in Cardiovascular Diseases) coordinated by the World Health Organization. This study comprises, in a defined geographical or administrative entity, an infarction Registry, two or three population surveys and two or three surveys concerning the treatment of the acute phase of myocardial infarction. It is a ten-year study conducted by 39 collaborative centres in 4 continents. The main hypotheses of this study have not yet been verified, as some centres have not completed the 10 years of infarction recording and/or the last population survey. However, the results collected to date and reported in about ten publications grouping all centres, and more than 500 articles published by various centres, demonstrate the wealth of precious information for clinicians provided by this public health project. For example, the infarction Registry demonstrates marked regional differences in myocardial infarction rates in the population and therefore marked differences in acute coronary bed requirements. The Registry also confirms the higher mortality rates in women and at the end of infarction compared to men. Population surveys can be used to follow the course of the main coronary risk factors and to compare the levels of risk factors in different centres. Regional differences clearly show that a more or less aggressive approach to primary prevention is required. Finally, the presence of an infarction Registry and population surveys allow the elaboration of case-control study protocols, several examples of which are mentioned by the authors. All of these techniques will be able to more clearly define the aetiology of coronary heart disease and, consequently, the reduction of this disease in the population by adequate primary and secondary prevention.