We have examined 24 human aortas aged 46∼90 years obtained from autopsies. Most exhibited gross lesions of some degree on the lumenal surface. Using hot alkaline treatment (0.1 N NaOH) at 70∼75oC for 5 hours, we extracted and quantitated elastin portions from the aortic wall in 3 different segments (UTA=upper thoracic aorta, LTA=lower thoracic aorta, AA=abdominal aorta). We have found UTA had 70.6%⁑1.39 (SE), LTA 61.6%⁑1.94 (SE), AA 49.2%⁑1.84 (SE) elastin respectively based on wet weight. The differences between segments are statistically significant (p＜0.05, 0.025). However, there is no significant correlation between the age of the patients and the relative amounts of elastin in each segment. We have also observed the structure of elastin in the internal elastic lamina (IEL) and tunica media (TM) with SEM (scanning electron microscopy), and discovered that the IEL shows various forms of elastolysis- broken sheets, discontinuity, various sizes of lumps, vesicles, and possible newly formed elastin in the aortic lesions (Song and Roach submitted to YMJ). From these studies we conclude that elastin in the aortic wall remains well balanced quantitatively with age in spite of evidence suggesting vigorous degeneration and regeneration in the atherosclerotic lesions.