Elevated serum levels of lipoprotein(a) [Lp(a)] confer an increased risk of coronary artery disease (CAD) and have been confirmed as a strong and independent risk factor for this disease. This case-control study was to determine the significance of elevated Lp(a) levels for the existence of CAD by systematically recording cardiovascular risk factors in diagnostic coronary angiography in a group of patients. Two hundred thirty seven consecutive patients (175 men, 62 women, aged 61+/-10 years) which comprised 24 acute myocardial infarction (AMI), 76 unstable angina (UA) and 137 stable angina (SA) who underwent coronary angiography, were used as cases. One hundred seventy normal healthy volunteers (95 men, 75 women, and aged 58+/-15 years) were used as controls. Lp(a) concentration were measured by an immunoturbidimetric method (Roche Diagnostics, Switzerland). There was a significant difference between Lp(a) levels in UA compared with the control subjects (44.2+/-49.0 vs. 27.6+/-25.3 mg/dL, p = 0.0006). When we compared SA and the control group (35.6+/-31.3 vs. 27.6+/-25.3 mg/dL, p = 0.0139) there was a significant difference between these two groups. UA patients also had a significantly higher prevalence of abnormal Lp(a) (>30 mg/dL) compared with the normal healthy control group (43.2% UA vs. 28.8% control, OR = 1.90, 95%CI = 1.08-3.32, p = 0.0248). SA patients also had the same finding as UA patients in a higher prevalence of abnormal Lp(a) when compared with the control group (45.2% SA vs. 28.8% control, OR = 2.04, 95%CI = 1.27-3.27, p = 0.0028). These data further support the role of Lp(a) in atherosclerotic coronary disease and the pathogenesis of acute coronary syndromes.