Telomere length and telomerase have an important role in normal and malignant hematopoiesis. Telomere erosion can lead to chromosome end fusion and thereby contribute to genomic instability during tumorigenesis. Thus, like complex chromosomal aberrations, telomere length may be a prognostic factor in hematopoietic malignancies. A paper by Sieglova et al. in this issue of Leukemia Research reports on the prognostic impact of telomere shortening in bone marrow (BM) and peripheral blood (PB) specimens of myelodysplastic syndrome (MDS) and MDS converted-AML patients (pts). Their results underline the importance to study telomere biology together with cytogenetics, genomic and proteomic profiling as prognostic factors, in order to improve risk-adapted therapy of MDS and AML pts.