This article addresses the issue of health inequalities and the measures allowing to reduce them. Starting from the observation that, in Switzerland like in the rest of the world, health gaps between the riches and the poorest are still very marked, this article questions the role that health promotion and prevention can play in the fight against this phenomenon. The main approaches allowing to reduce inequalities are presented and illustrated with examples : the universal approach, the targeted approach and proportionate universalism. This last approach appears as the ideal towards which all health promotion and prevention actions should converge in order to reduce health inequalities all along the social gradient. However, its translation into prevention measures remains subject to interpretation. Therefore, the article ends with a set of recommendations for the elaboration of measures aiming to reduce health inequalities.