The prevalence of modifiable cardiovascular risk factors (systemic hypertension, diabetes mellitus, cigarette smoking, low-density lipoprotein [LDL] cholesterol greater-than-or-equal-to 160 mg/dl and high-density lipoprotein [HDL] cholesterol < 35 mg/dl) was determined in 321 men < 60 years of age (mean +/- standard deviation 50 +/- 7) with premature coronary artery disease (CAD) documented at coronary angiography. The prevalence of these risk factors was markedly different than in the Framingham Offspring Study population, used here as a comparison group. In the patients with CAD, only 3% had no risk factor (other than male sex), compared with 31% in the Framingham Offspring Study subjects. Most patients with CAD (97%) had greater-than-or-equal-to 1 additional risk factor. When the patients with CAD were divided by age groups (40 to 49 years [n = 109], 50 to 59 [n = 191]), no significant differences were observed in the prevalence of risk factors between the young and older patients. The prevalence of systemic hypertension (41 vs 19%, p < 0.001), diabetes mellitus (12 vs 1.1%, p < 0.001), cigarette smoking (67 vs 28%, p < 0.001) and HDL cholesterol < 35 mg/dl (63 vs 19%, p < 0.001) was markedly higher in the patients with CAD than in Framingham Offspring Study subjects, whereas the prevalence of LDL cholesterol greater-than-or-equal-to 160 mg/dl was not significantly different between patients with CAD and Framingham Offspring Study subjects (26 vs 26%). The use of beta-adrenergic blockers was associated with a decreased prevalence of elevated LDL cholesterol and an increased prevalence of low HDL cholesterol, compared with patients not receiving this class of medication. When applying the guidelines of the National Cholesterol Education Program to patients with established CAD, only 52% had total cholesterol levels greater-than-or-equal-to 200 mg/dl and thus nearly half (48%) would not undergo further screening for lipoprotein abnormalities. In the group of patients with a total cholesterol < 200 mg/dl, 75% had a low HDL cholesterol (< 35 mg/dl). It is recommended that in men with established CAD, and in those with greater-than-or-equal-to 1 additional risk factor, fasting triglyceride and HDL cholesterol levels be determined in addition to total cholesterol.