Autonomic nervous system plays an important role in the regulation of mammalian heart, and it is divided into the sympathetic and parasympathetic (vagal) subsystems. The parasympathetic (vagal) control of the atria involves modulation of chronotropic, dromotropic and inotropic activities, but the role of the parasympathetic innervation of the ventricles is still unclear. There is a common misconception that the sympathetic nerves innervate all over the heart; while the parasympathetic nerves only innervate the superventricular part of the heart, but not the ventricles. Recent evidence indicates that the cholinergic innervation of the left ventricle is functionally very important in some mammalian species. The present article reviews the evidence of vagal control in the ventricles from the anatomy and histochemistry, molecular biology, and function areas. Additionally we overview the vagal (muscarinic) regulation of cardiac contractile function and its signal transduction.