To evaluate the prevalence and risk factors of asymptomatic carotid artery disease, we analyzed a sample of 909 men and women (aged 40-79 years) drawn from the community-based Bruneck Ischemic Heart Disease and Stroke Prevention Study. For the four decades of age (40-49, 50-59, 60-69, and 70-79 years), respective prevalence rates as assessed by duplex scanning were found to be 8.2%, 39.7%, 66.4%, and 82.5% in men and 3.3%, 22.3%, 48.7%, and 76.7% in women. High-grade stenosis (> 80%) classified by Doppler criteria was twice as frequent in men (2.4%) as in women (1.1%). Age and sex were found to be particularly strong and independent predictors of asymptomatic carotid artery disease. Accordingly, separate logistic regression models were developed for both men and women in the elderly (65-79 years) and middle-aged (50-64 years) groups. Systolic blood pressure turned out to be the only attribute with independent significance in all subgroups examined. Cigarette smoking, recorded as pack-years, emerged as the leading risk factor of carotid atherosclerosis in men. Serum fibrinogen levels were found to be highly indicative of carotid artery disease in elderly men and women. For apolipoprotein B predictive significance was observed in the middle-aged populations, whereas apolipoprotein A-I had a protective effect in elderly women. Diabetes mellitus completed the risk factor profile for elderly men. In summary, the relation between cardiovascular risk factors and asymptomatic carotid artery disease showed a dynamic dependence on sex and age. These findings may help to improve the efficacy of risk prediction in the general population and facilitate well-directed preventive measures.