Stem cell Research has become a priority in the 21st century for the development of regenerative medicine. Now we have launched a nation-wide project strongly supported by the Korean government as the 21st Century Frontier R&D Program. Stem cells, either adult or embryonic, could give rise to a wide variety of the differentiated cells, which could be applied to the treatment of various types of incurable diseases. Although we cannot clearly foresee the end point of stem cell research, we are convinced that our efforts would bear fruitful products for the future medicine Using these new techniques for the well-being of our society, we have to make an effort to draw a consensus from every field of interests, such as academic leaders, religious circles, judicial world and citizen. Somatic cell nuclear transfer technology has been used to generate animals with a common genetic composition. The isolation of pluripotent human embryonic stem cells and breakthroughs in somatic cell nuclear transfer in mammals have raised the possibility of establishment of cloned human embryonic stem cells. This concept, known as “therapeutic cloning” refers to the transfer of the nucleus of a somatic cell into an enucleated donor oocyte. We had made the world’s first cloned human embryos and had isolated from one of them a colony of stem cells.