To achieve a more complete understanding of the molecular mechanisms underlying tumor radioresistance, we established a radioresistant cell line from the human larynx squamous cell carcinoma cell line Hep-2 after long-term radiation induction. The biological features of the resulting cell lines were characterized. cDNA microarray technology was used to measure the alterations of gene expression in the radioresistant cells. We found that certain genes associated with DNA repair, cell cycle, apoptosis, etc. were significantly changed. In particular, genes related to telomeres, such as POT1, were significantly altered. Radioresistant cells had higher telomerase activity and longer telomeres than their parental cells. Our research suggests that telomere function is a novel hallmark of cellular radiosensitivity, and the mechanistic link between telomere maintenance and radiosensitivity may involve the genes and pathways we implicated in this study.