Inotropic agents are substances used to improve cardiac output and end-organ perfusion in severe forms of acute heart failure. However, inappropriate use of inotropic agents may be associated with severe adverse effects and death. Despite clear indications to restrict their use to acute heart failure patients presenting with signs of end-organ hypoperfusion, the current use of inotropes is very frequent and often unnecessary. This chapter reviews mechanisms of action of current and future inotropes (including catecholamines, phosphodiesterase-III inhibitors, calcium sensitizers, cardiac myosin activators, and istaroxime) and discusses their clinical use in acute heart failure.