The progress of nuclear transfer technology, we can create cloned animals. And recently from this same technology we can possible to establish nuclear transfer embryonic stem cells (ntES cell). From our experiments we can establish mouse ntES cells, which any kind of cell type and strain and sex. And ntES cell has very similar ability like ES cells that has capacities for in vitro differentiation and in vivo germline transmission. The ntES cell made from donor somatic cells, which are very useful for therapeutic cloning Because of no immune rejection. Especially for human, it have high expectation from this new opportunity for rejuvenation of the ageing or diseased body. However, even for cloned animals the efficiency is so low and that have many problems. So, it necessary to do more analysis of ntES cell can work normal and safe before clinic.