The aim of this article was to review different methods that are used for the evaluation of human and animal embryos' quality. Techniques for the production in vitro of various mammalian species embryos have been developed worldwide. Using modern methods for maturation of oocytes, fertilization and embryos' culture in vitro about 30-40% of bovine and 10-20% of human oocytes develop to blastocyst stage and can be used for transfer. Evaluation of embryos' quality is problematic not only for every researcher involved in embryology but also for every clinician who wants to select the best embryos for transfer. Lithuanian researchers and clinicians could also apply these worldwide popular methods for the evaluation of embryos' quality.