Effects of the glycerol addition and removal medium containg 10% sucrose on the mouse embryo survival after freezing in a liquid introgen container were determined using the FDA test. The summarized results are the following. 1. The FDA score was higher (P<0.05) when embryos were frozen in the glycerol addition medium with sucrose that the one without it(3.4 vs 3.0). 2. No difference in the score was found between the glycerol removal medium containing 10% sucrose(3.2) and PBS＋10% sucrose(3.3). 3. The score was higher(P<0.01) at morular stage than blastocyst stage of embryos.