Human Neural Stem Cells (hNSCs) are excellent candidates for in vitro and in vivo molecular, cellular, and developmental research, and also for ex-vivo gene transfer and cell therapy in the nervous system. However, hNSCs are mortal somatic cells, and thus invariably enter an irreversible growth arrest after a finite number of cell divisions in culture. It has been proposed that this is due to telomere shortening. Here, we show that long-term cultured (up to 4 years) v-myc perpetuated hNSC lines do preserve short but stable and homogeneous telomeres (TRF and Q-FISH determinations). hNSC lines (but not strains) express high levels of telomerase activity, which is activated by v-myc, as demonstrated here. Telomerase activity is not constitutive, becoming non-detectable after differentiation (in parallel to v-myc down-regulation). hNSC lines also maintain a stable cell cycle length, mitotic potential, differentiation and neuron generation capacity, and do not express senescence-associated beta-galactosidase over years, as studied here. These data, collectively, help to explain the immortal nature of v-myc-perpetuated hNSC lines, and to establish them as excellent research tools for basic and applied neurobiological and translational studies.