Using the model of breast cancer Ehrlich ascites tumor in mice, we showed that a sigle intraperitoneal injection of cardiac glycoside digoxin 1 h before the intraperitoneal injection of cisplatin increased the anticancer effect of the cytostatic drug more than twice when recalculated for the dose. It is assumed that the modifying effect of digoxin is determined by the direct inhibition of glycolysis in tumor cells. Taking into account the design of the study, we consider promising the clinical evaluation of the effectiveness of digoxin as a modifier of cisplatin efficiency in intracavitary therapy of ascites cancers with pleural and abdominal dissenmination.