Human individuals often exhibit important differences in their sensitivity to ionising radiation. Extensive literature links radiation sensitivity with impaired DNA repair which is due to a lack of correct functioning in many proteins involved in DNA-repair pathways and/or in DNA-damage checkpoint responses. Given that ionising radiation is an important and widespread diagnostic and therapeutic tool, it is important to investigate further those factors and mechanisms that underlie individual radiosensitivity. Recently, evidence is accumulating that telomere function may well be involved in cellular and organism responses to ionising radiation, broadening still further the currently complex and challenging scenario. © 2006 Wiley Periodicals, Inc.