This paper makes a socio-historical analysis of the determinants of health on the basis of the different ideas that are held about it. It examines the methodological and practical part played by these different ideas in the past and in the present, and the conclusion is reached that health is a sociobiological process historically determined. With the foregoing definition as a starting point, the author reviews the validity of primary care as a "key" strategy for attaining the goal of health for all by the year 2000.