The aim of the study is to analyze the influence of combination of pyrimidine and 3-hydroxypyridine derivatives — xymedon and mexidol, in comparison with kardioxane on the myocardial bioelectric activity and arterial pressure level in rats with Walker-256 carcinoma at the doxorubicin and paclitaxel chemotherapy. Material and Methods. Experiments have been carried out on 100 Wistar female rats of weight of 150-250 grams. Doxorubicin and paclitaxel were administered intraperitoneally in a dosage of 4mg/kg and 6mg/kg respectively on the 11th day of experiment. Xymedon (100mg/kg) and mexidol (50mg/kg) were administered separately and in combination with each other, starting with the 11th day of experiment for 10 days. Kardioxane was injected in the dosage of 80mg/kg 20 min before cytostatics. We estimated a myocardial bioelectric activity and arterial pressure level changes on the 11th and 22d day of the experiment. The results. Xymedon and mexidol combination has limited the development of myocardial electrical instability comparable to kardioxane action. This combination has prevented the appearance of metabolic changes of ischemic genesis in the heart more efficiently than kardioxane. Xymedon and mexidol have normalized QT interval dispersion corrected by heart rate less efficiently than kardioxane. Conclusion. The combination of xymedon and mexidol has reduced cardiotoxicity of antitumor therapy more efficiently than the separated use of these medicines or the use of cardioxane.