Three hundred and eighty nine autopsied human aortas were studied for lipid and fibrosis area at the 6 segments which were expected to receive different grade of mechanical stimuli. The fibrosis area was increasing with age with a jump-up at 50 years-old male and 60 years-old female. It was most prominent at lower half of the aortic arch and anterior half of the abdominal aorta with an acceleration by hypertension, and showed a female predominancy at the abdominal aorta in higher age. The aMPS content estimated by both chemical and histochemical techniques, was increased at 30 to 40 years-old male and at 40 to 50 years-old female and decreased thereafter. The aMPS-age curve was identified as a differential of the fibrosis-age curve, and it means that aMPS promoted progression of fibrosis. Histochemical study proved proliferating fine collagen fibers in the location where aMPS was accumulated. Abundant aMPS was present at the intimamedia junction and its main components were chondroitin sulfates AC and B, and heparitin sulfate. Hyaluronic acid existed mainly along the elastic layers of media. They were decreasing after middle age, and atheromatous and old fibrotic lesions with poor cellularity contained less aMPS than the intact area.