Abstract: Transgenic swine, and compositions and methods for making and using same, are provided. Central to the invention are porcine (Sus scrofa) embryonic stem cell lines and methods for establishing them. Cells of such lines are transformed with exogenous genetic material of interest and then used to provide chimeric swine, which have germ cells comprising the exogenous genetic material. The chimeric swine are bred to provide transgenic swine. Transgenic swine of the invention can be used to provide human proteins or peptide hormones or can be used as xenograft donors.