The silicon (Si) content and glycosaminoglycans (GAG) of normal, fatty streaks and atheroma of human aortic intima was measured. The Si content in fatty streaks and/or atheroma was significantly higher than in normal human aortic intima (P less than 0.05). The GAG content in human aortic intima was inversely correlated with the severity of atherosclerosis as described in many reports. However, the percentage composition of dermatan sulphate (DS) in total GAG was found to increase with the advance of atherosclerosis, and was significantly higher than that in normal and fatty streaks (P less than 0.001, P less than 0.01, respectively). In human aortic intima, a significant negative correlation was seen between Si content and the content of each GAG except GlcUA-GalNAc-6-sulphate (CS-6-S), and a significant positive correlation was noted between Si content and the content of each lipid. Interestingly, the percentage composition of DS in total GAG showed a significant positive correlation with Si content in human aortic intima (r = 0.603, P less than 0.005). These results suggest the increase in Si in the aortic intima is related to the occurrences and/or progression of atherosclerosis, whether primary or secondary.