In recent years there has developed an increasing awareness of the occurrence of pulmonary arteriovenous fistulas of congenital and often familial origin, and one now finds reports in the medical literature of lesions recognized clinically and treated surgically. Such lesions are also called angioma, cavernous hemangioma and arteriovenous varix or aneurysm. They are probably not related to malignant hemangioma of the lung, which is rare and causes widespread metastases. It appears to be probable that all benign, congenital pulmonary angiomas are of the same general nature as those observed in cases of Rendu-Osler-Weber's disease, or hereditary hemorrhagic telangiectasia, perhaps better called heredofamilial angiomatosis. Some cases merely lack the lesions of the skin and mucous membranes. The familial incidence may not be traceable in the individual case because of atavism. The hereditary nature of the disease has been discussed recently by Moyer and Ackerman.1 Pulmonary arteriovenous fistulas were described at