Acute Heart Failure Syndromes are defined as the rapid progression, or de novo presentation, of heart failure signs and symptoms. When clinical signs of low cardiac output are present, therapy with positive inotropic agents in an acute cardiac care unit is mandatory. Three classes of inotropic drugs are currently available, including beta-adrenergic agonists (especially dobutamine), phosphodiesterase inhibitors (such as milrinone) and the recently developed calcium sensitizers (levosimendan). In this article, we summarize the mechanisms of action of these different classes of drugs, and also discuss important issues regarding their clinical indications and the potential risks associated with their use.