During a longitudinal study of Salmonella on pig farms in England conducted between 1997 and 2000 some of the participating farms introduced interventions to control Salmonella infection. Interventions such as, feed acidification and fermented liquid feed were not successful. The more successful interventions in terms of Salmonella control were in batch systems; dry cleaning accompanied by disinfection using 2% formaldehyde solution. In many cases the beneficial effects of the interventions were undermined by the introduction of pigs already carrying salmonellas, failure to disinfect walkways, ventilation systems and other farm equipment. The use of single interventions is unlikely to result in the control of Salmonella at the farm level.