Abstract: Garlic has been used for millennia in the traditional medicine practice of many cultures to treat cardiovascular and others disorders. In this study, mechanism of action of garlic on several excitable membranes have been discussed. three groups of isolated toads hearts were used to investigate the effect as well as the mechanism of garlic solution (4 g ml-1) on the physiological properties of the myocardium through the electrocardiogram (ECG) recordings. A significant decrease of the heart rate (negative chronotropism) accompanied by significant increase in the conduction time (positive dromotropism) were resulted following the garlic application and sustained 20 min. Several cases of heart block were recorded after 10 min from garlic perfusion. Application of atropine didn`t abolish the effect on the myocardium. Moreover, an increase of the ventricular voltage has been noticed after 10 min from the garlic application. The calcium-channel blocker verapamil apparently abolished the positive inotropic effect of the garlic. Smooth-muscle activity was studied before and after garlic application (4 g ml-1). An increase of the spontaneous contraction of rabbit-duodenum was established by garlic solution. Blockade the M3 muscarinic receptors of the smooth muscle by atropine sustained normal contraction. Perfusion of toad gastrocnemius-muscle/sciatic-nerve preparation with (4 g ml-1) garlic solution weakened the mechanical contraction of the muscle without recovery. Pretreatment with the nicotinic receptor antagonist gallamine sustained normal contraction of the skeletal muscle.