Levosimendan belongs to the class of calcium sensitizers, which exhibits its positive inotropic effects by increasing the affinity of troponin from the myocardium to calcium without additional myocardial oxygen demand, what favorably distinguishes it from catecholamines and their negative effects (myocardial ischemia, arrhythmias, vasoconstriction, hyperglycemia). In 2000, the drug was first used for the short-term treatment of decompensated chronic heart failure. After more than 20 years, the clinical use of levosimendan has covered a wide area among patients with pathology of the cardiovascular system and its use has gone far beyond the primary indications. To date, the drug has been studied in more than 200 randomized trials in patients with various clinical profiles: acute decompensation of chronic heart failure, progressive heart failure, acute myocardial infarction, cardiogenic shock, therapy of low cardiac output syndrome in cardiac surgery, perioperative use in pediatric cardiac surgery, septic shock, pulmonary hypertension, right ventricular failure, Takotsubo cardiomyopathy, patients with mechanical circulatory support devices. This review highlights the pharmacological features of the drug and key randomized clinical trials on the use of levosimendan in various categories of patients, in addition to officially recommended indications. The article also provides a brief overview of current and planned randomized trials.