This is the lecture given by Jorge Jiménez MD, Minister of Health at the 1990 Chilean Congress of Internal Medicine. He states that clinicians today are directing their attention to epidemiology and to the community health problems, focusing their medical activity towards primary prevention of diseases. Knowledge emerging from evolutionary pathology, natural history of diseases, human genetics, the influence of environment upon health and human behavior, enriches the new outlook of epidemiology. The concept of promotion of health overlaps the classical concept of prevention.