Prior exercise research and the recently completed HF-ACTION (Heart Failure and A Controlled Trial Investigating Outcomes of Exercise Training) trial indicate that regular exercise represents an effective therapy in the management of patients with stable chronic heart failure (HF) due to left ventricular systolic dysfunction. This review summarizes the results from these studies and provides a guide for prescribing exercise. Regular aerobic-type exercise training improves exercise capacity; does not worsen and may, in fact, mildly improve cardiac function; and partially improves other physiological abnormalities that develop because of chronic HF (eg, autonomic and skeletal muscle function). Regular exercise is safe, improves health status, and modestly reduces (∼15%) combined risk for cardiovascular death or HF-related hospitalization. Even greater physiological and clinical benefits appear likely in patients with HF who adhere to a higher volume of exercise (eg, 6 MET-hr per week). The exercise regimen should include an aerobic-type activity performed at least 30 minutes, 5 or more days per week, and at an intensity approximating 55% to 80% of heart rate reserve. Resistance training should be considered for patients who first demonstrate they are able to tolerate aerobic exercise training. Common to other interventions that also rely on human behavior, long-term adherence to exercise in patients with HF remains a challenge and requires additional research to determine strategies aimed at improving compliance. Areas of needed research include identifying which patient subgroup(s) benefits the most and determination of the optimal intensity, duration, and frequency of exercise needed to maximize clinical benefits and attenuate fatigue.