Levosimendan was introduced in Sweden as an i.v. infusion for the treatment of acute heart failure or refractory symptoms of chronic heart failure in cases where conventional treatment (e.g., diuretic or ACE inhibitor) is not sufficient. Levosimendan is the (R)- enantiomer of simendan that belongs to the same class as pimobendan (Boehringer Ingelheim). Levosimendan is an innovative myofilament calcium sensitizer that increases myocardial contractility by selectively binding to the N-terminus of troponin C and by stabilizing the Ca2+-bound conformation of this contractile protein. It also activates ventricular and arterial adenostne triphosphate-regulated potassium channels which causes vasodilatation in vascular smooth muscle and protects myocardium against infarction. Its low phosphodiesterase III inhibiting activity is probably not responsible for its positive inotropic, lusitropic and dilating effects. Unlike other cardiotonic drugs, levosimendan is able to produce positive inotropic effects without prolonging myocardial relaxation or increasing the incidence of malignant arrythmias. It was clinically shown to have a lower risk of mortality in patients with heart failure when compared to placebo and dobutamine. Since it has a larger potential, levosimendan is currently under further clinical evaluation as a chronic treatment for congestive heart failure.