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The cloning of livestock is performed by the nuclear transfer of early embryonic stages into prepared oocytes in order to obtain a high number of genetic identical animals. As the most important technical steps there are maturation and enucleation of the oocytes, isolation of single blastomeres or karyoplasts of the donor embryo, transfer of the nucleus-containing membrane vesicle under the zona pellucida of the recipient cell, and fusion of the recipient cell and blastomere or karyoplast. Until now, the largest clone which is known exists of seven bulls. The efficiencies of the particular methodical steps have to be improved. More knowledge of the activation of oocytes, nucleus differentiation and availability of determined cell cycle-stages of mitosis is required. The combination of embryo cloning, cryopreservation of embryos and non-surgical embryo transfer is required for basic research and animal breeding.