This intervention program tested the applicability and effects of intensive physical exercise and a low fat diet on progression of coronary atherosclerotic lesions and stress-induced myocardial ischemia in patients with stable angina pectoris. Eighteen patients participated in this program for 1 year; they consumed a low fat, low cholesterol diet (less than 20 energy % fat, cholesterol less than 200 mg/day) and exercised for greater than 3 h/week. Change in coronary morphology was assessed by angiography and digital image processing; stress-induced myocardial ischemia was measured by thallium-201 scintigraphy. Results were compared with those in patients receiving "usual care." In the intervention group, significant regression of coronary atherosclerotic lesions was noted in 7 of the 18 patients; no change or progression was present in 11 patients. In patients receiving usual care, regression was detected in only 1, with no change or progression in 11 patients (different from intervention, p less than 0.05). There was a significant reduction in stress-induced myocardial ischemia, which was not limited to patients with regression of coronary atherosclerotic lesions. Thus, regular physical exercise and a low fat diet may retard progression of coronary artery disease; however, improvement of myocardial perfusion may be achieved independently from regression of stenotic lesions.