In this review we briefly describe recent knowledge of telomerase (predominately human telomerase) activity regulation mechanisms. We also point telomerase complex components localization in cells and discuss the enzyme activities that are independent of telomere elongation. The paper includes the overview of human diseases correlating with reduced telomerase activity, short telomeres and rapid telomeres shortening. We describe in details the possibilities of exogenous hTERTgene transcription activation by different natural and synthetic compounds as well as hTERTgene transfection effects. Such exogenous activation cause increasing proliferative potential of the cells and might be used in cell therapy. It must be noticed that elevated hTERT gene expression, especially in the case of hTERTgene transfection, might be the cause of cell malignesation. In this regard strict constraining criteria in medical application of different methods of telomerase activation must be developed.