Telomeres help to maintain chromosomal stability and integrity. They are progressively lost, conditioning aging and mortality. Telomerase enzyme activation stabilizes the telomere length, permitting the proliferation of cancer cells. Four papers are reviewed dealing with increased expression of telomerase associated with increased labelling index of MIB-1 (Ki-67) and malignancy in astrocytomas, ependymomas, and oligodendrogliomas. Telomerase expression can be utilized for differentiating malignant from benign tumors with histological resemblance. The significance of telomerase in tumor progression is discussed within the field of brain neoplasias.