While most of the deaths occurring during labor and in the early puerperium are said to be due to hemorrhage, toxemia, heart disease or other less common obstetric and medical causes, a few fatalities remain unexplained even after careful postmortem examination.1In the absence of pathologic chemical and anatomic changes such deaths are often considered, without proof, to be on a functional basis. It is the object of this paper to attempt to fill this gap in our knowledge and to point out that some of these obscure deaths form a disease entity with its characteristic causation, symptoms and pathologic changes by (a) presenting the clinical histories of 8 patients to show that they form a distinct group, (b) demonstrating in them a pathologic-anatomic basis for this series of symptoms and (c) demonstrating the experimental production of this disease in animals, the disease in them having a similar symptomatology and