Aims: The main goal of this review-article was to shed light on the impact of senescence on thyroid carcinogenesis, a promising but still neglected field. Source of data: PubMed database and Google Scholar search was performed for English language articles with terms: ionizing radiation exposure, thyroid cancer, radiation signature, RET/PTC, senescence and radiation-induced senescence. We have no date restrictions. Summary of findings: Ionizing radiation (IR) is undoubtedly the most well characterized risk factor for thyroid cancer of the papillary histotype and its pivotal role as senescence inducer has been proposed. A paradoxical role of senescence on carcinogenesis – a barrier to cancer cell proliferation in early steps and a driving force to cancer progression by secreting proinflamatory cytokines and matrix degrading enzymes – is the heart of the matter of age- related cancer and bring to life new insights to thyroid cancer research field. This review-article briefly points out the major findings that link ionizing radiation to thyroid carcinogenesis, highlighting the molecular alterations mediated by acute and chronic radiation exposure in thyroid cells. Conclusions: Evidences provided by our group and other few reports suggest that, like other oncogenic stimuli in different cell types, IR induces a senescent phenotype in thyroid cells, what could represent an initial barrier to transformation. However, how senescence could contribute to tumor progression still remains elusive. The comprehension of these mechanisms could not only help elucidating thyroid cancer initiation and progression, but could also indicate new therapeutical targets.