Sterigmatocystin is a mycotoxin structurally similar to aflatoxin and is a precursor to aflatoxin B1 (AFB1) and G1 (AFG1) in their biosynthesis. It is synthesized by 55 different mold species belonging to phylogenetically and ecologically diverse generas. It has been found in various foodstuffs even after the processing and in indoor humid spaces and the dust. Target organs during acute exposure are the kidneys and liver. The LD50 for oral exposure is 160 mg kg-1 b.w. The currently known mechanism of action is associated with the formation of exo-epoxides and the formation of DNA adducts and it is therefore assumed that the mechanism of action is related to the occurrence of oxidative stress. This study investigates the role of sterigmatocystin in the generation of oxidative stress in male Wistar rats. Rats were treated once with steigmatocystin at three different doses: 1/4, 1/8, and 1/16 LD50 (40, 20, and 10 mg kg-1 t.m.). Different parameters of oxidative stress have been measured in kidney and liver tissues and blood plasma: the activities of the enzyme superoxide dismutase, catalase and glutathione peroxidase, the concentration of reduced glutathione and malondialdehyde. The results show that sterigmatocystin causes oxidative stress. However, further studies are needed to discover the mechanism of sterigmatocystin toxicity.