Levosimendan is a new cardiac enhancer that exerts positive inotropic effects on the failing heart mediated by calcium sensitization of contractile proteins as well as peripheral vasodilatory effects mediated by opening of ATP-sensitive potassium channels in vascular smooth-muscle cells. Levosimendan is the most well-studied calcium sensitizer in the real clinical practice, producing greater hemodynamic and symptomatic improvement in patients with acute heart failure syndromes (AHFS) than those with traditional inotropes. Immunomodulatory and anti-apoptotic properties of levosimendan may be an additional biologic mechanism that prevents further cytotoxic and hemodynamic consequences of abnormal immune and neurohormonal responses in AHFS. Recent mortality trials showed that levosimendan does not improve short- and long-term prognosis in AHFS in comparison to dobutamine or placebo. However, in patients with a previous history of CHF and on beta-blocker on admission, levosimendan seems to have a beneficial effect on short-term mortality. According to the recent guidelines of the European Society of Cardiology, levosimendan is indicated in patients with symptomatic low cardiac output HF secondary to cardiac systolic dysfunction without severe hypotension (Class IIa, Level of Evidence B).