We investigated the effects of hypercholesterolemia, hypertension, and diabetes mellitus, which are major coronary risk factors, on the angiographic morphology of coronary artery lesions in 204 patients with previous myocardial infarction or stable-effort angina: 39 patients with hypercholesterolemia (serum total cholesterol > 240 mg/dl) without hypertension and diabetes, 51 patients with hypertension without diabetes and hypercholesterolemia, 24 patients with diabetes without hypertension and hypercholesterolemia, and 90 patients without any of these 3 risk factors (control). Patients without coronary artery lesions were excluded. The severity of coronary artery lesions is expressed as the Gensini score and the morphology is classified according to Rosch's classification. The distribution of coronary artery lesions did not differ significantly between the 4 groups. The Gensini score was significantly higher in the hypercholesterolemia group than in the other groups (p < 0.05). Short concentric lesions were more frequent in the hypercholesterolemia group than in the control group (p < 0.01), and tubular regular lesions were more frequent in the hypertension and diabetes groups than in the control group (p < 0.01). These results suggest that hypercholesterolemia has a greater influence on the severity of coronary artery lesions than does hypertension or diabetes, and that the progression of coronary atherosclerosis may differ among patients with these risk factors.