Peculiarities of the pharmacokinetics of mafedine sodium salt upon intraperitoneal (i.p.) and intravenous (i.v.) administration to laboratory mice were studied. A high-performance liquid chromatography (HPLC) method for its quantitative determination was proposed. Mafedine sodium salt was found to have a short biological elimination half-life after both i.p. and i.v. administration (15.73 and 6.98 min, respectively) and high i.p. bioavailability (~94%). Features of the alpha-2-adrenomimetic activity of mafedine sodium salt could be elucidated by further searches for and investigations of its metabolites and their pharmacokinetics.