In order to investigate the prevalence of atherosclerosis in Mexico, high resolution ultrasound and color Doppler flow imaging of carotid arteries were carried out in a group of participants in CUPA project, a cohort study started in 1989 among persons 60 years and older living permanently in a high rise in México City. Imaging studies included identification of 4 atherosclerosis related abnormalities: 1) intima media thickness; 2) kinkings and tortuousness; 3) non-stenosing plaques; and 4) significant carotid stenosis (> 50%). Analysis of 198 Doppler ultrasonographic studies in 56 males and 142 females showed an overall prevalence of atherosclerosis related lesions of 65.6%, with increasing frequency by age groups: 33% in younger than 65 year-old, 71% in 65-74 years, and up to 88% in the 75 years and older group. The prevalence of high grade stenosis was low (6%) whereas the overall frequency of non-stenosing plaques and intima-media thickness was higher than 60%. Intima-media thickness was more common in males while non-stenosing plaques and high grade stenosis were more frequent in females. However, there were not significant differences among women and men when atherosclerotic lesions were analyzed by age groups. This is the first report on the prevalence of atherosclerosis in a Mexican population using ultrasonography. Findings of the investigation document the high prevalence of atherosclerosis among elderly resident in Mexico City.