The pathologic entity known as pseudomembranous enterocolitis has received much attention in the literature of recent years; yet a brief scanning of bibliographies on the subject will make the reader aware not only that the pathogenesis of this lesion remains an enigma but that there is a persistent trend toward identification of pseudomembranous enterocolitis with staphylococcal enteric infections secondary to antimicrobial therapy. It is evident from this study of 14 cases, first, that pseudomembranous enterocolitis is a pathologic entity not necessarily identifiable with or a sequel of staphylococcal enterocolitis, and, second, that an impairment of the blood supply of a part of the gastrointestinal tract caused by local or systemic vascular abnormalities may be a common denominator in the production of fatal pseudomembranous inflammation of the bowel. History Excellent reviews have been given by Newman1and other authors.2,3Though pseudomembrane formation in the gastrointestinal tract has long been