During the summer of 2003, France experienced an unprecedented heat wave. This heat wave had a greater impact in large urban areas due to the urban heat island effect. Meteorological data for thirteen major cities representative of all metropolitan climates (Bordeaux, Dijon, Grenoble, Le Mans, Lille, Lyon, Marseille, Nice, Paris, Poitiers, Rennes, Strasbourg, and Toulouse) were provided by Météo-France. Two studies on mortality were conducted, one based on deaths recorded by civil registration and the other on hospital mortality data. An initial analysis reveals significant disparities among the cities. Paris, Lyon, Dijon, and Le Mans experienced a very clear spike in excess mortality during the heat wave. Lille and Rennes were less affected. These observations will need to be supplemented by an in-depth analysis of the correlation with meteorological and climate data over a longer period.