Three functional elements are required for the stable transmission of eukaryotic chromosomes: replication origins, centromeres and telomeres. In the yeast Saccharomyces cerevisiae the DNA sequences defining each of these elements are known. The simplest and most widely conserved of these sequences is that of the telomere. As the name implies, the telomere is the end of a linear eukaryotic chromosome. Two of the main functions of the telomere are to prevent DNA loss as a consequence of replication and to prevent interactions with other chromosomal ends. Thus, telomeres play a major role in maintaining chromosome stability and consequently they have been considered as likely to be involved in some aspects of chromosomal aberration formation. The involvement of telomeric DNA sequences in stabilizing normal and broken chromosome ends, in 'hot spots' for aberration formation and in delayed chromosomal instability will be reviewed here drawing on material presented at the Workshop and the published literature.