[en] Objective: To investigate the efftcets of low dose X-ray radiation on the activity of the reactive oxygen species (RCS) and mitochondrion membrane potential (ΔΨm) in spermatogenic cells of mouse testes. Methods: The RCS activity and ΔΨm in the cells were measured indirectly by flow cytometry with 2', 7'- dichlorofluorescin diacetate (DCFH-DA) and Rhodamine 123 probes. Results: The RCS activity increased with the increase of irradiation doses 12 h after irradiation with different doses of X-rays compared with 0 Gy (P<0.05); but the ΔΨm decreased with the increase of irradiation doses compared with 0 Gy (P<0.05). After irradiation with 0.075 Gy X-rays, the RCS activity increased with time prolongation compared with 0 h (P<0.05), reached the peak at 12 h later, and kept the higher level; but ΔΨm decreased with the time prolongation, compared with 0 h (P<0.05), and reached the lowest level at 12 h later, then recovered to the normal level gradually. Conclusion: Low dose radiation can induce the the increase of RCS and decrease of ΔΨm in spermatogenic cells of mouse testes, and has dose- and time-effect regulations. (authors)