['To study whether cancer stem cells promotes resistance of laryngeal squamous cancer to irradiation mediated by hypoxia.', 'Hep-2 cells were respectively cultured in hypoxia and normoxia environment, and the express of HIF-la was detected by western blot. Then they were radiated with different doses of gamma-rays. After that we detected growth inhibition ratio with MTT assay, cell circle and ratio of CD133+ cells with Flow cytometry at different times.', 'MTT assay showed that inhibition ratio of the hypoxia group was lower than that of the normoxia group after different doses of gamma-rays at each time point, and the difference was significant 24 h after 10 Gy irradiation (P < 0.05). The results of Flow cytometry demonstrated that cells of the two groups were arrested at G1 phase, and cells ratio in G1 phase of the hypoxia group was higher than that of he normoxia group after 10 Gy irradiation. The ratio of CD133-positive cells was higher in the hypoxia group than in the normoxia group after radiation, and difference was significant 24 h after 10 Gy irradiation (P < 0.05). In each group, the ratio of CD133-positive cells became higher after radiation than that before radiation (P < 0. 05).'] Does [ Cancer stem cells promote resistance of laryngeal squamous cancer to irradiation mediated by hypoxia ]?