In vitro, He-Ne laser show a modifying response of cells to ionizing radiations. So there is a need to show the effect of He-Ne laser (632.8nm), Ultraviolet radiation UVC (250nm) and He-Ne laser pre and post irradiation against the UVC radiation of Mitotic index of femur and in vivo to DNA of testis in Mice. In this study 100 albino male mice were divided into five groups, the first group Control which have (10) number of mice, the second group Laser which have ( 27 ) number of mice were

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... into three groups different time periods (5, 10, 15 min), the third group Ultraviolet radiation (UVC) which have ( 9 ) number of mice and duration of exposure one hour, the fourth group laser (5, 10 and 15 min) + UVC (1h) which have ( 27 ) number of mice, with ½ hour time interval between the two irradiations and the finally group UVC (1h) + laser (5, 10, 15 min) which have ( 27 ) number of mice, with ½ hour time interval between the two irradiations was monitor the effect of radiation on mice according to the classification totals above after various time periods (7, 14, 21 days). Mitotic index as shown increase the percentage of Mononucleus and less increase of Dinucleus after exposure of the radiation according to the classification totals above. The He-Ne laser per-irradiation show a protection properties, which appeared the DNA damage against UVC light irradiation. But the He-Ne laser pre-irradiation against UVC irradiation farther more reduce the DNA testis damaging. UVC shows a damaging effect on the DNA. This damage was reduced by the He-Ne laser preirradiation. Thus Laser pre-irradiation may be attributed to the induction of endogenous of radio protectors or which may be involved in DNA damage repair.