Background: Carotid plaque is associated with cardiovascular morbidity and mortality in old aged people or patients with hypertension. We sought to evaluate the impact of carotid artery plaque on long-term prognosis in patient with coronary atherosclerosis. Methods: A total of 1698 consecutive patients, (mean 59.7짹10.9 years old, 921 male (54.2%) who underwent coronary angiography and carotid artery scanning for carotid plaque, were followed up for mean 26.9짹21.3months. Study subjects were divided to two groups according to the presence of carotid plaque. Results: Patients who had carotid plaque (n=649, 345 males (53.2%)) were likely to be older (64.4짹9.4yrs old vs. 56.8짹10.8yrs old, p<0.001), had higher fasting blood sugar level (131.3짹58.5mg/dL vs. 120.0짹47.0mg/dL, p<0.001) and blood urea nitrogen (17.5짹8.1mg/dL vs. 15.9짹6.5mg/dL, p<0.001), had lower high-density lipoprotein cholesterol level (41.9짹10.8mg/dL vs. 43.2짹10.8mg/dL, p=0.022), had higher incidence of hypertension (57.7% vs. 44.3%, p<0.001), diabetes (32.3% vs. 20.3%, p<0.001), dyslipidemia (53.2% vs. 44.4%, p=0.001), and old myocardial infarction (13.5% vs. 3.8%, p<0.001) than those without carotid plaque (n=1049, 576 males (54.9%)). Patients with carotid plaque had higher mortality (3.1% vs. 1.0%, HR 6.01, p=0.014), higher restenosis rate (13.8% vs. 6.6%, HR 15.28, p=0.0001), and higher hospitalization for congestive heart failure (2.4% vs. 0.7%, HR 4.91, p=0.0267) than those without carotid plaque. Cox regression analysis including carotid plaque, hypertension, diabetes, dyslipidemia, and old myocardial infarction revealed that the presence of carotid plaque was the only predictor (RR 1.349, p=0.020) for mortality in study patients. Conclusion: The presence of carotid plaque was associated with an increased mortality in patients with coronary artery disease. This study suggests that carotid plaque is an important predictor for mortality than the conventional cardiovascular risk factors such as hypertension, diabetes, dyslipidemia in patients with coronary artery disease.