Since 1987, a surveillance system for human salmonellosis has been in operation in Mayenne, involving the Departmental Health and Social Affairs Service (DDASS), clinical laboratories, and general practitioners in the department. Its purpose is to contribute to understanding the local epidemiology of these infections, to track their trends over time, and to assist in the implementation of preventive measures. The data presented below cover the years 1991–1996, the period during which the system became fully operational. (adapted from the text).