The intimate connection between telomerase regulation and human disease is now well established. The molecular basis for telomerase regulation is highly complex and entails multiple layers of control. While the major target of enzyme regulation is the catalytic subunit TERT, the RNA subunit of telomerase is also implicated in telomerase control. In addition, alterations in gene dosage and alternative isoforms of core telomerase components have been described. Finally, telomerase localization, recruitment to the telomere and enzymology at the chromosome terminus are all subject to modulation. In this review we summarize recent advances in understanding fundamental mechanisms of telomerase regulation. (C) 2011 Elsevier BM. All rights reserved.