Timiryazevskaya, Moscow, 127550 Russia; 22, ul. 800-letiya Moskvy, Moscow, 127247 Russia Acknowledgements: Bovine embryos cloning using zona-free NT was led by M.I. Prokof’ev and carried out in the Biotechcenter of V.A. Afanas’ev Research Institute of Fur Farming and Rabbit Breeding (Moscow Province, Leninskii Region, Gorki Leninskie). <...> Supported by LLC «Bioline Pharmtorg» (Moscow) A b s t r a c t The review is dedicated to one of the relevant and widely discussed topics of modern biotechnology, namely cloning of mammals. <...> Particularly, the success and problems of the somatic nuclear transfer (SCNT) are discussed herein. <...> The advantages and disadvantages of a commonly used SCNT and zona-free modification are compared based on special publications and the data obtained in our experiments. <...> The most promising targets for the SCNT are reproductive cloning, therapeutic cloning and fundamental science. <...> One of the reasons is a low yield of healthy offspring in mammals, for example, average yield in cattle is about 9 % of cloned embryo transfers result in birth of healthy offspring. <...> It is assumed that deviations in the development of cloned fetuses are caused by disorders in genomic reprogramming of a somatic cell nucleus, which results in significant disturbance of gene expression particularly in placenta. <...> Even though there are several practical techniques that allow to increase effectiveness of SCNT, reprogramming of the nucleus demands further study as one of the fundamental problems of developmental biology. <...> Second problem that hinders practical application of SCNT method is complexity of the conventional technique, which was introduced about 30 years ago by S.M. Willadsen (1986). <...> At the same time significant progress has been achieved in the so called zona-free nuclear thansfer method (zonafree NT), where oocytes are freed from zona pellucida before enucleation. <...> They used blastomeres of bovine embryo for electrofusion. <...> We have improved zona-free NT method for cattle embryo cloning (G.P. Malenko et al., 2006). <...> In the available publications there are no references about zona-free NT use by other researches in Russia while worldwide it is considered more simple, effective and reproducible method <...>