On December 23, 1999, the French Institute for Public Health Surveillance (InVS) informed the Somme Departmental Directorate for Social Affairs (DDASS) that three strains of Salmonella enterica serotype Paratyphi biotype B (d-tartrate positive), isolated on November 5, November 19, and December 3, in the same hospital laboratory in the Somme, had been received for serotyping at the National Reference Center for Salmonella and Shigella (CNRSS). These strains were associated with three patients hospitalized in a long-term care facility affiliated with a hospital. Upon being contacted by the DDASS, the hospital’s Committee for the Control of Nosocomial Infections (CLIN) reported having identified three additional cases (isolated on December 12, 13, and 22, 1999), involving two patients hospitalized in the long-term care facility and one patient staying in a short-term care unit of the hospital. A food and environmental investigation had already been initiated to determine the source of these cases and to implement appropriate control measures. The results of the food, veterinary, and microbiological investigations show that this outbreak is attributable to the consumption of frozen ground beef from a contaminated batch, distributed with insufficient and non-compliant pre-cooking treatment.