In the present study, the cardiovascular activity of the aqueous extract of Gynostemma pentaphyllum Makino leaves was investigated in the anaestetized guinea-pigs and has been compared with two of its isolated gypenosides (III, VIII) and with verapamil, a well-known Ca-antagonistic drug. The results obtained showed that the intravenous administration of the decoction of G. pentaphyllum (2.5, 5 and 10mg/kg) produced a protective effect against pitressin-induced coronaryspasm, arrhythmias and pressor response. Extract also increased the dose of ouabain required to cause ventricular tachyarrhythmias and lethality. Further extract reversed ouabain-induced persistent ventricular tachycardia and restored sinus rhythm in a dose-dependent manner. The results obtained have also shown that gypenosides III and VIII caused similar protective effects in both experimental models used; however, the duration of the action is lower than that of the extract containing corresponding quantities of gypenosides III and VIII.