In spite of the fact that we do not have any cloned mammal in the Czech Republic yet, this contribution of our workers to solve given issue is not small. The method of core transfer is basically very simple. From the oocyte in metaphase II are removed chromosomes and subsequently is put the core of selected cell.To achieve success, it is necessary to comply with a number of principles: perfectly aware of both cell cycle components, identify mutual interactions and mainly perform all steps with high precision. Our works had been mainly focused on knowledge and understanding of questions mentioned above and certainly contributes also to the fact that the world manager to clone a number of mammalian somatic cell nuclear transfer. The aim of our paper is to summarize and perform the most important achievements that were published by VUŽV specialists.