-Although poultry is recognized as the major source of food-poisoning caused by Salmonella, pork also contributes to human infections. This study was therefore undertaken in order to develop a reliable serological method for the evaluation of the Salmonella status of piglets. A complete ELISA was performed using lipopolysaccharides of Salmonella Typhimurium, Anatum, Hadar and Infantis because these serovars were representative of the serogroups isolated from 30 contaminated fattening farms. S. Enteritidis was also added because of its importance in human infection and to include the O : 9 antigen. This method potentially detects 100% of infected pigs. A significant correlation was found between this serological method and the bacteriological data from mesenteric lymph nodes (p = 0.01). In addition, both sensitivity and specificity were high (97% and 94% respectively). The ELISA test was therefore used in a cross-sectional study on 4 farms to evaluate when pigs became contaminated: seropositive pigs were only found for the 20 week old finishing pigs. The antibody response to Salmonella in piglets was also investigated: maternal antibodies persisted until 7 weeks of age and post-Salmonella contamination seroconversion was detected from 8 weeks of age onwards.ELISA / Salmonella / pig / epidemiology Résumé -Mise au point d'une méthode ELISA complète basée sur des lipopolysaccharides de plusieurs sérogroupes permettant de détecter tous les porcs infectés par des salmonelles. Bien que la volaille soit la principale source d'intoxication alimentaire par les salmonelles, le porc contribue aussi à la contamination humaine. Cette étude a été menée pour mettre au point une technique sérologique permettant d'évaluer le statut infectieux des porcelets vis-à-vis des salmonelles. Une technique ELISA dite complète a été élaborée avec des lipopolysaccharides de Salmonella Typhimurium, Anatum, Hadar et Infantis, sérovars représentatifs des sérogroupes isolés dans 30 élevages engraisseurs contaminés. S. Enteritidis a été ajoutée en raison de son importance dans les infections humaines et afin d'inclure l'antigène O : 9. Cette méthode permet de dépister potentiellement 100 % Vet. Res. 31 (2000) [481][482][483][484][485][486][487][488][489][490] 481