Clinical application of physical exercise has developed into an evidence-based therapeutic option for cardiovascular diseases, especially coronary artery disease (CAD) and chronic heart failure (CHF). In CAD regular physical exercise training partially corrects endothelial dysfunction and leads to an economization of left ventricular function. Meta-analyses have shown a reduction of angina pectoris symptoms and a decrease of total and cardiovascular mortality by regular aerobic exercise training. Endurance training for CHF reduces cardiac afterload by correcting peripheral endothelial dysfunction und leads to a better left ventricular function. In addition exercise training reduces the adrenergic tone and the stimulation of the renin-angiotensin-aldosterone system in CHF. Exercise training provides positive effects on the metabolism and function of skeletal muscle (e.g. reduced inflammation and oxidative stress). Supervised regular physical exercise training in CHF is safe and has improved the morbidity in clinical studies. Thus aerobic exercise training is an important component of therapeutic management of stable CAD and CHF with a class 1a recommendation in the current guidelines.