A statistically significant difference in the cumulative survival of Wistar rats born in different seasons has been shown: animals born in late November - early December had an average lifespan by 24,8% longer, a minimum lifespan by 14,3% longer, and a maximum lifespan by 20,7% longer in comparison with animals born in April. The geroprotective effect of the technique of thymus tissue transplantation into the immune privileged anterior chamber of the eye in animals born both in November and April has been shown.