Since the hallmark report of the PCR-based telomeric repeat amplification protocol (TRAP) in 1994, there has been a flurry of investigations of telomerase activity on normal, benign, premalignant and cancerous samples representative of the various stages of tumorigenesis. Basic research and technological advances in human genetics, biochemistry and model systems have brought much progress towards the understanding of human infectious, hereditary and somatically acquired diseases. The knowledge of carcinogenesis has increased very rapidly in the past few years, particularly with the development of automated molecular biologic analysis of tumors and preneoplastic lesions. Despite the wide variety of studies on the potential use of telomerase as a cancer biomarker, the variability of reported telomerase activity and the lack of a transferable detection method have prevented it from becoming a routine clinical application. Real-time PCR is a clinically transferable method and the advancement of real-time measurements of telomerase will facilitate moving telomerase activity and technologies towards clinical validation. It is expected that the next 5 years will see telomerase integrated into the initial detection and follow-up monitoring of cancer patients. The hope is that the use of telomerase will finally translate into a diagnostic to help realize longer survival and a better quality of life.