The results of infertility treatment by extracorporeal fertilization remain constantly low. Most resorts IVF -ET carries two ? three selected embryos in the second day of culture at the stage of four blastomeres . Evaluation of the quality of such embryos is made on the basis of morphological characteristics and the rate of cell division . However, embryos with normal appearance of morphological and divisions , selected according to these criteria may be incorrect cytogenetically and will not be implantowały in the uterine cavity . The main challenge of modern reproductive medicine is to develop methods to obtain and identify embryos with full developmental potential and implantation . In the article the author presents an evaluation strategy for quality embryos throughout their development przedimplatacyjnego : evaluation of oocyte pronuclear stage , dividing embryos , blastocysts . In the future, as the embryos selected for transfer should lead to a high pregnancy rate and low rate of multiple pregnancies . It is hoped that the transfer of one embryo in IVF -ET programs a reality.