Plasma cholesterol was measured in 10,672 participants of a cholesterol screening program in Atlanta, Georgia. The participants were typically health conscious, as evidenced by the low prevalence of current cigarette smoking (13%), but more than 21% of the men and 33% of the women over age 50 had cholesterol levels in excess of 240 mg/dl, placing them at moderate to high risk for coronary artery disease. Results revealed a pronounced dose response relationship between cigarette smoking and cholesterol in men of all age groups and in women of premenopausal age, whereas levels were similar in ex-smokers and those who had never smoked. Risk analysis revealed a strong positive association between cholesterol and the prevalence of nonfatal myocardial infarctions. Notably, patients with newly diagnosed hypercholesterolemia reduced their cholesterol an average of 36 mg/dl under care of physicians. These results indicate that cholesterol screening coupled with physician follow-up and treatment can have a substantial impact in lowering cholesterol and its attendant risk of cardiovascular disease.