Objective To study the efficacy of two vitrification solutions for mouse morulae Methods Good morulaes of NIH mice were collected and used to test toxicity of the vitri- fication solutions EDS40 (40% ethylene glycol,18% dextran and 0.5 mol sucrose) and EFS40 (40% ethylene glycol,18% ficoll and 0.5 mol sucrose). Fine vitrified morulae were packaged in 0.25 mL plastic straws and immersed into liquid nitrogen and cryopreserved for about 2-3 months. Then the straws were heated rapidly, washed in Ham’s F12 medium and cultured. The viability was determined by morphology and blastocyst formation after being cultured for 48 h. Some embryos were transplanted to recipients after being cul- tured for 12-14 h. The number of pregnant recipients and young born was counted and analyzed by Chi-squared test. Results The toxicity of EDS40 solution was significantly lower than that of EFS40 (P<0.05) and the number of embryos developed to the blastocysts after vitrification in EDS40 was significantly higher than in EFS40 (P<0.05). The number of zona pellucida and the number of pregnancy and birth integrated after vitrification cryopreservation had no significant difference between EDS40 and EFS40 (P>0.05). However, the embryo fine- ness rates after vitrification in EDS40 was significantly better than in EFS40 (P<0.01). Conclusion EDS40 solution has less toxicity and better cryoprotect effect on embryos than EFS 40. Objective To study the efficacy of two vitrification solutions for mouse morulae Methods Good morulaes of NIH mice were collected and used to test toxicity of the vitrification solutions EDS40 (40% ethylene glycol, 18% dextran and 0.5 mol sucrose) and EFS40 (40 % ethylene glycol, 18% ficoll and 0.5 mol sucrose). Fine vitrified morulae were packaged in 0.25 mL plastic straws and immersed into liquid nitrogen and cryopreserved for about 2-3 months. Then the straws were heated rapidly, washed in Ham’s F12 medium and The viability was determined by morphology and blastocyst formation after being cultured for 48 h. Some embryos were transplanted to recipients after being cultrued for 12-14 h. The number of pregnant recipients and young born was counted and analyzed by Chi- squared test. Results The toxicity of EDS40 solution was significantly lower than that of EFS40 (P <0.05) and the number of embryos developed to blastocysts after vitrification in EDS40 was significantly hi The number of zona pellucida and the number of pregnancy and birth integrated after vitrification cryopreservation had no significant difference between EDS40 and EFS40 (P> 0.05). However, the embryo fine-ness rates after vitrification EDS40 was significantly better than in EFS40 (P <0.01). Conclusion EDS40 solution has less toxicity and better cryoprotect effect on embryos than EFS 40.