Telomere shortening is an important risk factor for cancer and accelerated aging. The gold standard and most commonly used method for measuring telomere length determines an average terminal restriction fragment (TRF) size. This Southern blot-based method is laborious and requires a large input of DNA and time. We have developed a simple and reproducible method to measure absolute telomere length. This method is based on Cawthon’s quantitative real-time PCR (qRT-PCR) assay, which, in its original format, produces a relative measure of telomere length. Cawthon first described the use of qRT-PCR to measure telomere length in 2002.