Hosting mega sporting events (MSEs), such as the Olympic Games, requires host cities and their countries to make considerable investments that are rarely cost-effective in themsel- ves. The benefits for local populations lie mainly in the positive legacy that these invest- ments are intended to leave in the long term, particularly in terms of urban renewal and new infrastructure (facilities, transport, housing, green spaces, etc.). This article explores the links between MSEs and how they can impact health through urban planning, focusing on the most relevant health determinants in this context, such as physical activity and social cohesion. To this end, we have drawn up a logical pathway of the impacts on health and well-being and conducted an analysis of the existing literature. It appears that an intersec- toral approach involving different stakeholders and skills is essential, as well as integration into the local environment and partnerships with local actors. Above all, the ambivalent nature of the health impacts identified calls for a clarification of the conceptual framework of “legacy” and how it can be measured.