Mucoid vasculopathy of unknown etiology. A new vascular disorder with generalized deposition of abnormal amounts of acid mucopolysaccharide (AMPS) material in arteries, veins, and vasanervorum has been observed in a large number of autopsies at the author's institution. It is unlike any of the known vascular diseases and has emerged as a distinct disorder of vascular connective tissue. This has been named "mucoid vasculopathy of unknown etiology." This hitherto unreported entity is described here. 