AbstractThe article describes effects of telomerization on proliferative activity in cultured cutaneous diploid fibroblasts obtained from an adult men aged 57 years. It is shown that the cells in the control culture initially divide quite actively, but starting from the 27th to the 40th passages, the rate of their division decreases and the time to reach the monolayer increases by about 2 times, and starting from the 42nd passage, the time to reach the monolayer increases by 4-10 times (up to 16-40 days). In a single case, an increase in the doubling time of control non-thelomerized cells was recorded up to 30 times (136 days). The introduction of the telomerase gene allowed cells maintain a high rate of cell division to about 45-47 passages. At the same time, the culture with the telomerase gene exceeds the control culture by 10 passages. Rate of growth the cells with telomerase gene after 48 and up to 57 passages slowed down by 10-18 times (up to 40-73 days). At the 47th passage in the control culture and at the 57th passage in the experimental culture, the cells practically stopped dividing and their number did not increase. The results show that the inclusion of the telomerase gene in adult fibroblasts does not always cancel the limit of cell divisions.