The post-thaw development rates of the embryos frozen in the 2.0 and 3.0mol/L glycerol in PBS 20?S 0.5mol/L sucrose were 51.4% and 44.1%, significantly higher than those of other groups.The post-thaw develop-ment rate of the embryos frozen in the 0.5mol/L sucrose in PBS 20?S 2.0mol/L glycerol was 47.7%,significantly higher than that of other groups. The development rale of the embryos frozen slowly was 48.8%, significantly higher than that of embryos frozen rapidly.The post-thaw development rate of 2-cell embryos was the lowest in four stage embryos. The survival rate of morula was higher than that of 4-cell and blastocyst. The development rate of in vitro fertilized embryos was significantly lower than that of in vivo fertilized ones. A total of 112 frozen-thawed embryos obtained from in vitro fertilization were transferred to recipients, 2/9 of whom became pregnant.