By imposing a limit on the proliferative lifespan of some human cell types, telomere loss and the subsequent onset of replicative senescence has been proposed to contribute to age related disease. Whilst there is a large of body of in vitro data to reveal the mechanisms by which telomere erosion triggers senescence, technical limitations have hampered our ability to understand the full extent of telomere erosion in vivo. Thus far we have evidence of age related telomere loss; however the lack of resolution of existing technologies does not allow us to determine if telomere erosion is extensive enough to trigger replicative senescence. This coupled with the considerable inter-individual heterogeneity and the overlap in telomere lengths between young and elder individuals render the significance of this loss unclear. Therefore the link between telomere erosion and human ageing remains theoretical and any evidence will at best be correlative. However recent technical developments, including quantitative telomere fluorescence in-situ hybridisation (Q-FISH) and the PCR based single telomere length analysis (STELA), have increased the resolution of telomere length analysis. These technologies promise to provide the evidence required to address the full extent and significance of telomere loss in the human ageing process. Here we revue published data on the dynamics of telomere erosion with age in the human body.