AimsThe control of Salmonella in pig production is necessary for public and animal health, and vaccination was evaluated as a strategy to decrease pig prevalence. Methods and ResultsThe study examined the efficacy of a live Salmonella Typhimurium vaccine, administered to sows on eight commercial farrow-to-finish herds experiencing clinical salmonellosis or Salmonella carriage associated with S. Typhimurium or its monophasic variants. Results of longitudinal Salmonella sampling were compared against eight similarly selected and studied control farms. At the last visit (similar to 14months after the start of vaccination), when all finishing stock had been born to vaccinated sows, both faecal shedding and environmental prevalence of Salmonella substantially declined on the majority of vaccinated farms in comparison to the controls. A higher proportion of vaccine farms resolved clinical salmonellosis than controls. However, Salmonella counts in positive faeces samples were similar between nonvaccinated and vaccinated herds. ConclusionsThe results suggest that maternal vaccination is a suitable option for a Salmonella Typhimurium reduction strategy in farrow-to-finish pig herds. Significance and Impact of the StudySalmonella vaccines have the potential to reduce the prevalence of Salmonella in pigs and result in a reduction of human cases attributed to pork.