This study was carried out to investigate the survival rates of late mouse molulae frozen in the state of vitrification and then thawed after equilibrating them separately in EFS 40, GFS 40 and DFS 40 at 1$0^{circ}C$. The results obtained are as follows : 1. Freezing in the state of vitrification and thawing late mouse molulae after equilibrating them at l0$0^{circ}C$ in EFS 40 for 30 seconds, one minute and two minutes, we obtained survival rates of 76.7%, 96.7% and 100%, respectively. 2. Freezing and thawing them after equilibrating at 1$0^{circ}C$ in GFS 40 for 30 seconds, one minute and two minutes, we obtained survival rates of 60%, 96.7% and 10%, respectively. These results are as similar as in the case of EFS 40. 3. Freezing and thawing them after equilibrating at l$0^{circ}C$ in DFS 40 for 30 seconds and one minute, we obtained survival rates of 62.1% and 0%, respectively. These results represent lower survival rates than those obtained with EFS 40 and GFS 40. In conclusion, even equilibrating late mouse molulae in EFS 40 and GFS 40 at 1$0^{circ}C$ for more than one minute gives a survival rate of more than 97%, while equilibrating them in DFS 40 at 1$0^{circ}C$ for more than one minute results in a 0% survival rate, which means that DFS 40 has a strong toxicity.