The ends of linear eukaryotic chromosomes, telomeres, distinguish natural chromosome ends from DNA double stranded breaks and thus promote genome stability. Telomeres comprise a repetitive DNA skeleton, which is wrapped in specific protein complexes. Recent data indicate that an additional building block of telomeres is RNA and that the longstanding idea that telomeres are silent genomic regions needs to be overturned. Mammalian telomeres are indeed transcribed into RNA molecules, which remain associated with telomeric chromatin, suggesting RNA-mediated mechanisms in organizing telomere architecture.