To evaluate the prevalence and extent of carotid atherosclerosis in a general healthy population, duplex ultrasound imaging was performed in 909 men and women aged 40-79 years as part of the prospective Bruneck Ischemic Heart Disease and Stroke Prevention Study. Atherosclerotic lesions were found in 47.8% of men and 36.3% of women. Sex differences in the prevalence rates were most pronounced from age 40 to 60 years with a convergence occurring in the 7th decade. The age range of 60-69 years was found to be the crucial period for the development of advanced carotid artery disease. The frequency of internal carotid artery stenosis (> 50%) in elderly men and women (60-79 years) was 10.5 and 5.5%. In nonstenotic carotid artery disease the lumen diameter turned out to be a useful indirect measure of the vascular status.