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During a radio collaring study of a reintroduced swift fox population, carcasses of deceased foxes were collected and thorough necropsy examinations undertaken. A total of 48 carcasses were collected by field workers in the southeastern area of Alberta, and the southwestern area of Saskatchewan, Canada. All carcasses were examined grossly; histological examination was also undertaken for those which were not severely autolysed or depredated. Foxes were aged by a tooth sectioning technique. Stomach contents were collected to determine food sources, which varied from insects (used heavily by young foxes in the summer and early fall) to small mammals and carrion. Field data and necropsy findings were used to elucidate the cause of death, with trauma being by far the most common. Trauma due to predation was widespread with coyotes, eagles and occasionally badgers being the suspected predators. Vehicular trauma was a significant cause of death, especially in young of the year foxes. Most animals examined were in good body condition; suspected starvation was rare and associated with the stress of release in one case, and a jaw fracture in another. Incidental findings included parasitism by ticks and intestinal ascarids.