A significant increase in histopathologic nonspecific chronic aortitis was found when 100 autopsy specimens from 1965 were compared with series from 1974 and 1980. The chronic aortitis was correlated with furosemide diuretic administration during the last hospitalization. Furosemide is albumin bound, produces vasodilation, and is suspected of having induced a subclinical haptenic immunologic reaction in about one third of those treated.