The cardiotonic effect of the secretion of the toads Bufo viridis Laur. skin glands and discharged bufadienolidines has been studied in the experiments on dogs under anaesthesia. It has been shown that the toad poison and bufadienolidines administered intravenously produce a marked cardiotonic and vasotonic effect, increasing the intraventricular and aortal pressure, the rate of pressure growth in the ventricles and the contraction index of the myocardium. The cardiotonic effect of poisons has also been noted in the model study of cardiac insufficiency caused by the bandaging of the coronary artery, it has greater effect than that of the cardiac glycoside corglycon.