Abstract: Objective：To explore the posibility of single human compacted embryo and blastocyst transfer. Methods：There were 231 cycles of human frozen-thawed embryo transfer （FET） in the Center of Reproductive Medicine of Northern Jiangsu People′s Hospital. The study compared embryos implantation rate，clinical pregnancy rate and multiple pregnancy rate among cleavage-stage embryo group，compacted embryo group and blastocyst group of human frozen-thawed embryo. Results：The number of embryo transfer is significantly lower in the compacted embryo group compared to the cleavage-stage embryo group [（1.35±0.50) vs.（1.73±0.59），t=-4.902，P＜0.001）]，the embryos implantation rate and clinical pregnancy rate of compacted embryo group are higher than cleavage-stage embryo group （49.58% vs. 23.00%，χ2=24.567，P＜0.001；53.41% vs. 34.15%，χ2=7.805，P=0.005）. The embryos implantation rate of blastocyst group is higher than cleavage-stage embryo group （46.88% vs. 23.00%，χ2=8.214，P=0.004）. There was no statistics difference on the multiple pregnancy rate among the three groups（χ2=2.231，P=0.328）. Conclusions：Compacted embryo or blastocyst transfer causes a satisfactory embryo implantation rate and clinical pregnancy rate per transfer cycle，and minimizes the multiple pregnancy rate at the same time. They are very useful for single embryo transfer.

Key words: Embryo transfer, Reproductive techniques, assisted, Blastula, Frozen-thawed embryo transfer