Four grups of twenty growing Wistar rats were irradiated with either UV, IR, UV+IR light or were not irradiated (control). Ten rats from each group received a diet supplemented with 0.6% of L-ascorbic acid. The effects of the mega-dose of vitamin C were evaluated by changes in the antioxidative/oxidative status. UV and IR radiation promoted oxidative DNA degradation in rat livers and supplementation with ascorbic acid strengthened the prooxidative effects on DNA oxidation in rats irradiated with UV or IR light. Vitamin C also increased the tiobarbituric acid reactive substances (TBARS) concentration in rats from all groups except UV+IR-irradiated. The combined UV+IR light, corresponding to solar radiation, had no negative effects on redox homeostasis in rats. Furthermore, L-ascorbic acid showed antioxidative properties by increasing the concentration of Total Antioxidative State (TAS) in plasma, hence decreasing the production of reactive oxygen species (ROS) in UV+IR irradiated rats.