In looking at increases in disability-free life expectancy we examine the scope and evolution of social inequalities in health. As early as the end of the 18th century, Moheau had already emphasised the differences in life expectancy according to profession but it wasn't until much later that official statistics could confirm them. Despite the growing concern related to this phenomenon, the data are lacking for tracking its evolution and understanding its causes. The indicators of disability-free life expectancy that we established for socio-professional groups allowed us to respond to certain outstanding questions. The results of this study are summarised in this article. They serve to re-open the debate around the problems involved in measuring social inequalities and their place in public health.