The effects of exercise on the progression of eight chronic diseases or medical conditions are reviewed. In the case of coronary artery disease (CAD), there is some suggestive evidence that exercise is associated with a survival advantage. Exercise does not consistently increase blood flow in peripheral vascular disease, nor does it improve lung function in patients with chronic obstructive pulmonary disease. However, it is associated with increased physical work capacity in these two conditions. Preliminary studies suggest that exercise may be beneficial in the management of pulmonary secretions in patients with cystic fibrosis. Exercise has no therapeutic role in acute exacerbations of rheumatoid arthritis, but in the chronic stages, exercise that does not cause pain may be beneficial. Exercise is the focal point of chronic pain syndrome programs. With exercise programs, patients with chronic pain can increase physical work capacity with a decrease in complaints of pain. Patients with osteoporosis appear to benefit from a carefully programmed low-level exercise program that avoids back flexion exercises. Blood glucose, hypertension, and serum lipid levels improve with exercise in patients with dialysis-dependent renal failure.