the GISSI studies, characterized by the wide participation of Italian Coronary Care Units (about 4/5 of those existing in the country) and by the adoption of protocols closely following clinical practice, have allowed the recruitment of large numbers of patients over short periods of time, ensuring not only a high statistical power but also the evaluation of the treatments' effects in real populations of patients with acute myocardial infarction, avoiding the artificial conditions of patient selection commonly shared by usual clinical experimentations. The creation of a permanent network of clinical monitors within Centres allowed to ensure a reliable and correct process of data collection.