Proteins can become oxidatively modified by various reactions involving reactive oxygen species (ROS) produced by normal metabolism. Carbonylation reaction is of special importance because of its irreversibility and therefore can be seen as a marker of damaged proteins. It has been established that an increase in age increases the level of proteome carbonylation in mortal human cells, which is not true in the case of immortal human cells. The aim of this study is to show the correlation between chronological age of mortal (human fibroblasts BJ) and immortal cell lines (immortalized human keratinocytes HaCaT, SV40 transformed human fibroblasts MRC-5 SV40) and oxidation damage in their proteome and to identify differences in their ability to resist oxidative stress. Oxidative stress has been carried out by treating four subcultures of listed cell lines with different doses of UV-C radiation and protein carbonylation was analyzed in order to determine the carbonylation levels present 0 h and 24 h after treating four subcultures of mortal and immortal cell lines with UV-C radiation. It has been found that mortal human cells possess inherently elevated levels of proteome carbonylation which causes the resistance to oxidative stress in those cells to decrease during aging. It is likely that immortal human cell lines have mechanisms that enable them to efficiently degrade oxidatively damaged proteins which results in greater ability to resist oxidative stress induced by UV-C radiation.