This thesis is an investigation of the behaviour of newly weaned group housed swine following infection with 'Salmonella'. Sixty Landrace/Yorkshire pigs were housed in rooms of five animals over three trials. One pig per room was randomly selected and received an oral dose of ' Salmonella' Typhimurium. Direct observations occurred daily; pigs received fecal, cleanliness, and bite lesion scores in addition to rectal temperature measurements. Video analysis determined the time budget of the pigs and location within the pen, as well as aggression and abnormal behaviour. Few behavioural changes were evident between seeder animals and penmates through measurement of direct observation or time budgets. At the farm level, dirtier pigs may indicate that a gastrointestinal problem such as 'Salmonella ' might be moving through a group of animals. The multidrug resistant ' Salmonella' strain significantly increased lying and aggression. Animals on the tetracycline diet increased lying and decreased the amount of rooting behaviour.