Technical Abstract: The ingestion of uncooked infected meat is considered important in the epidemiology of Toxoplasma gondii infection in humans and little is known of the prevalence of viable T. gondii in meat used for human consumption in the U.S. In the present study, viable T. gondii was isolated from 51 of 55 of pigs destined for human consumption. Hearts and tongues (500 g) from 55, 6-mo-old pigs from a farm in Massachusetts were bioassayed for T. gondii by feeding to T. gondii-free cats. Feces of these cats were examined for shedding of T. gondii oocysts. Fifty one of 55 cats fed pig tissues each shed 25 to 810 million T. gondii oocysts in their feces. Two of these cats consumed tissues of pigs that were shown to be seronegative with the Sabin-Feldman dye test, the modified agglutination test, and the Western blot. Results indicate that until examination of meat for T. gondii infection is implemented in slaughter houses, all meat should be cooked according to industry guidelines before human consumption.