Although in the past the use of beta-blockers was considered inadvisable in patients with chronic heart failure, recent evidence strongly recommends the use of these drugs for chronic heart failure due to their positive effects on mortality and hospitalization. This paper analyzes some of the possible mechanisms responsible for the positive action of beta-blockers in heart failure. In fact, the effects of reducing sympathetic activity by beta-blockers on the myocardium, skeletal muscle, inflammatory system, metabolism of free fatty acids and glucose, insulin resistance, serum electrolytes, renal function and oxygen free radical generation are illustrated and discussed.