A procedure was developed to measure plasma and urine likviritin levels by reversed-phase high performance liquid chromatography. The likviritin pharmacokinetics was studied in rats after intravenous injection of the compound in a single dose of 1,3 and 10 mg/kg and after its oral administration in a single dose 50 and 500 rag/kg. It was shown that likviritin pharmacokinetics after i.v. injection within the above dose range was nonlinear and within every dose could be described by a two-compartmental model. Its nonlinear nature might be associated with saturated binding of the compound.