The cases in this series were selected on the basis of gross postmortem evidence of either recent infarction or fairly well circumscribed patches of fibrosis in the heart muscle. The fibrotic patches were all gross and were readily seen macroscopically; they were usually well marginated. The large majority averaged at least 3 cm. in the largest diameter. It is believed that these fibrotic patches or scars in most cases probably represented areas of old infarction, particularly in view of the high incidence of associated coronary sclerosis. At any rate, as, regardless of their etiology, they presented a definite pathologic entity, they were grouped together in this series. The one hundred cases selected comprised all cases in which the heart showed the aforementioned lesions in a series of nine hundred and forty-two necropsies performed at City Hospital from Jan. 3, 1928, to May 1, 1931. Thirty-two of the one hundred cases