By CHARLES L. CROCKETT, JR., M.D., DONALD SHOTTON, M.D., CHARLES G. CRADDOCK, JR., M.D., AND BYRD S. LEAVELL, M.D. H EMORRHAGIC diathesis due to idiopathic hypoprothrombinemia was reported first in 1941 by Rhoads and Fitz-Hugh.’ A case of this type has been admitted to the Pediatric Service of the University of Virginia Hospital five times between 1945 and 1948. In the first portion of this rep...