This disclosure provides a system for generating animal tissue with carbohydrate antigens that are compatible for transplantation into human patients. The tissue is inactivated homozygously for expression of .alpha.(1,3)galactosyltransferase, and comprises a transgene for .alpha.(1,2)fucosyltransferase. As a result, cell-surface N-acetyl lactosamine is not converted to the Gal.alpha.(1,3)Gal xenoantigen. Instead, it is converted to Fuc.alpha.(1,2)Gal, which is H substance, a self-antigen in humans. The tissue may also contain A or B-transferase, which will cause H substance to be converted into other ABO blood group antigens for compatibility with patients of the same blood type. This invention improves transplant compatibility of the xenograft tissue by lessening the risk of reactions resulting from xenoantigen and unconverted N-acetyl lactosamine acceptor determinants.