The pharmacokinetics of the total pool of coenzyme Q(10) (Co(10)), its oxidized (ubiquinone) and reduced (ubiquinol, CoQ(10)H₂) forms have been investigated in rats plasma during 48 h after a single intravenous injection of a solution of solubilized CoQ(10) (10 mg/kg) to rats. Plasma levels of CoQ(10) were determined by HPLC with spectrophotometric and coulometric detection. In plasma samples taken during the first minutes after the CoQ(10) intravenous injection, the total pool of coenzyme Q(10) and proportion of CoQ(10)H₂ remained unchanged during two weeks of storage at -20°C. The kinetic curve of the total pool of coenzyme Q(10) corresponds to a one-part model (R² = 0.9932), while the corresponding curve of its oxidized form fits to the two-part model. During the first minutes after the injection a significant portion of plasma ubiquinone undergoes reduction, and after 7 h the concentration of ubiquinol predominates. The decrease in the total plasma coenzyme Q(10) content was accompanied by the gradual increase in plasma ubiquinol, which represented about 90% of total plasma CoQ(10) by the end of the first day. The results of this study demonstrate the ability of the organism to transform high concentrations of the oxidized form of CoQ(10) into the effective antioxidant (reduced) form and justify prospects of the development of parenteral dosage forms of CoQ(10) for the use in the treatment of acute pathological conditions.