In Lille (a large city in northern France), the municipal council has set up an Health Observatory in order to provide health information on the city's population, promote educational health policies, foster the development of preventive actions and improve access to the healthcare system. The Observatory works with agencies involved in health in France, such as the CPAM ("Caisse Primaire d'Assurance Maladie", the state health insurer). The purpose of the present study was to describe care consumption by the inhabitants of Lille's 12 districts on the basis of data supplied by the local branch of the CPAM. By using principal component analysis and a hierarchical classification tool, we established a typology of districts according to care consumption. The results of this study can be used to improve decision-making, elaborate better health policies and promote social actions.