Genetic resistance to Salmonella infection in experimental animal models is well described. However, genetic resistance in domestic animals, which has potentially great value in terms of controlling Salmonella in the food chain, has been relatively poorly described. Recent advances in genetics and immunology have identified several factors that influence resistance in chickens and pigs in particular. Resistance to systemic salmonellosis in the chicken is encoded by a number of factors including Nramp1 (now termed Slc11a1) and a novel gene, SAL1 that leads to increased macrophage activity against Salmonella. Studies in outbred, and in particular, inbred chickens have revealed considerable differences in levels of colonization of the gastrointestinal tract and responses to vaccination. Factors influencing this appear to include innate immune function, MHC and Nramp. In pigs several immune factors, including polymorphonuclear cell activity, have been shown to influence resistance.