Ochratoxin A (OTA) and Citrinin (CTN) are nephrotoxic mycotoxins commonly found together in grain. The toxicity mechanism of OTA has not been fully explained, while the toxicity mechanism of CTN is all but unknown. Because they commonly appear together in nature and because it is hypothesized that oxidative stress is somehow included in their toxicity mechanisms, a research was performed on adult male Wistar rats which were treated daily with OTA (125 i 250 μg kg-1 bm x21), CTN (20 mg kg-1 bmx2) and resveratrol (20 mg kg-1 bmx21). The goals of the research were to establish whether CTN treatment induces oxidative stress, whether combined OTA and CTN treatment increases oxidative stress in tested animals and whether treatment with the antioxidant compound resveratrol can reduce the levels of oxidative stress induced by OTA and CTN. CTN treatment caused a reduction in glutathione (GSH) concentration levels in plasma samples and an increase of comet tail length in kidney samples. It has been established that CTN augments the effects of OTA by increasing malondialdehyde (MDA) concentration levels in plasma and liver tissue and especially in the kidneys where this effect is reduced by resveratrol treatment. GSH concentration levels are decreased in liver samples after treatment with both dosages of OTA, while kidney and brain samples display this reduction only after treatment with the higher dosage. The effect of resveratrol treatment is that a significant reduction in GSH concentration levels is found only in kidney samples. Since GSH concentration reduction was observed in all experiments with higher OTA dosages, the effect can be attributed to that mycotoxin. The effect of the combined OTA and CTN treatment on oxidative enzyme levels is ambiguous. Catalase activity was least sensitive to the effect of mycotoxins, while superoxide dismutase activity was most sensitive. DNA damage measured with the comet assay was prominent in animals treated with both mycotoxins with tail intensity being the better damage indicator. Treatment with resveratrol did not prevent DNA oxidative damage.