Lyme disease, or Lyme borreliosis, is a zoonosis found throughout the Northern Hemisphere. It is by far the most common tick-borne infection in Europe. The incidence of the disease varies greatly from country to country, and even within a single country, from region to region. To date, only sporadic epidemiological studies on this condition have been conducted in France, which do not allow for a precise determination of the disease’s incidence. However, the available information indicates that Alsace is a region where Lyme disease is widespread. For this reason, the Departmental Directorate of Health and Social Affairs (DDASS) of Haut-Rhin requested in 1999 that the Interregional Epidemiology Unit East (CIRE Est) study the prevalence of the disease in Alsace. Furthermore, in July 2000, the Institute for Public Health Surveillance (InVS) undertook a prioritization effort in the field of non-foodborne zoonoses with the aim of determining priorities and the resources to be deployed to improve knowledge, prevention, and control of these diseases. Lyme disease was among the 37 diseases analyzed, and, based on the criteria used for prioritizing diseases, Lyme borreliosis was included in the list of priority diseases for planning InVS actions due to the emerging nature of this condition and its potential severity. These various factors led the Cire Est to establish a Lyme disease surveillance network in Alsace with the objectives of describing Lyme disease and estimating its incidence in Alsace, as well as identifying the geographic areas most at risk in the region, in order to inform healthcare professionals and the public based on reliable data.