SOD, CAT, GSH-Px, GSSG-R, ascorbic acid, alpha-tocopherol, nonprotein- and protein-bound sulfhydryl compounds, and TBA-rs content in the liver, erythrocytes, and blood serum of rats treated with methanol after 6, 12, and 24 h and 2, 5, and 7 days were investigated. Furthermore, hematological parameters of erythrocytes were analysed. GSH-Px, GSSG-R, sulfhydryl compounds, and ascorbic acid in the liver, erythrocytes, and in blood serum were significantly decreased. In addition, Cu,Zn-SOD and tocopherol in erythrocytes were diminished, whereas TBA-rs in the three biological materials was enhanced. Simultaneously, erythrocytes amount, hemoglobin level, hematocrit, and MCV were reduced. These results indicate that methanol in rats leads to the impairment of antioxidant mechanisms in the liver, erythrocytes, and blood serum.