It was carried out to investigate the effect of the kind of medium, the concentration of serum added and the temperature of storage on the survival of mouse and bovine embryos preserved In vitro. The survival of frozen-thawed mouse embryos after cooling at 4$^{circ}C$ was also investigated. It was possible to preserve the embryos of mouse until 4 days and of cattle in a day without significant decrease of the survival rates. The survival rates of frozen-thawed mouse embryos after cooling at 4$^{circ}C$ over 3 days were below 20%.