The influence of ionol (100mg/kg) on the rate of superoxide generation (V) and activities of antioxidant enzymes: CuZn- and Mn-SOD, glutathione peroxidase (GSH-Px), glutathione S-transferase (GST) in different subcellular organelles of mice liver was studied. Ionol is shown to result in realiable a synchronous changes of all studied antioxidant enzyme activities in cytosol and whole blood. On the first day the level of these enzymes increased by 1.5 times and on the third day it returned to normal. The obtained data indicate retention of regulatory relation in antioxidant system in liver cytosol within the sector SOD-GSH-Px. In the mitochondria the Mn-SOD activity changes in antibate manner as compared CuZn-SOD activity, on the first day Mn-SOD activity decreases and remains on lowered level during the whole period investigated. In microsomes the value of V is found to be reduced. In the case of SMP on the first day after the administration of ionol V value didn't increase significantly. However, owing to Mn-SOD activity decrease the ratio V/A, showing the level of superoxide radicals in subcellular organelles grows 3-fold. In nuclei V value increases 4-6-fold during 1-3 hours after ionol injection. The data obtained show that administration of high dose of ionol to intact mice suppresses antioxidant enzyme system of mitochondria, induces abrupt production of superoxide radicals in nuclei and reduces of functioning of electron transport chaine in microsomes. The observed disturbances have short-lived character and are normalized during 3 days after administration of ionol. The toxic effects of ionol may be connected with the action of oxidative modification products formed in organism.