PROBLEM TO BE SOLVED: To provide viable pigs which lack any expression of functional α-1,3-GT; to provide procine cells, tissues and organs, which lack any expression of functional α-1,3-GT, for use in xenotransplantation or other biomedical applications; and to provide a method to select and screen for porcine cells, which lack galactose α-1,3-galactose epitopes on the cell surface.SOLUTION: This invention is the production of the first live pigs lacking any functional expression of α-1,3-galactosyltransferase. The invention provides the complete inactivation of both alleles of the α-1,3-galactosyltransferase gene in pigs, thus overcoming longstanding hurdle and making xenotransplantation a reality. Eliminating the expression of this gene, resulting in a lack of galactose α-1,3-galactose epitopes on the cell surface. This represents the first and major step in eliminating hyperacute rejection in pig-to-human xenotransplantation therapy. The invention also provides organs, tissues, and cells derived from such porcine animals, which are useful for xenotransplantation.