Abstract: Embryo viability assessment is critical when selecting single embryo to transfer. The first and the most extensive application is morphology scoring，including the scoring of oocyte，pronucleus，cleavage embryo and blastocyst. Though，recent years，targeted-metabolic analysis have been proposed as a useful tool for assessment of embryo，involving pyruvate acid，glycometabolism，amino acid turnover，soluble HLA-G and so on. Furthermore，metabolomic-profiling，by analyzing the metabolome of different embryo development stage，has showed the great application promising. But，the assessment only by morphology or metabolism can not ascertain the chromosome abnormality. So，the chromosome abnormality screeing have been a strategy to select viable embryo for transfernation. In brief，we still depend on morphology assessment as our first line approachs to embryo selection，other potential approaches need further investigation before using clinical trials.

Key words: Embryo transfer, Embryonic development, Evaluation studies, Metabolism, Genomics, Chromosomes, human, In situ hybridization, fluorescence