CONSIDERABLE modification has occurred in the point of view concerning recent myocardial infarction since its first adequate clinical description by Herrick.1There is therefore need for further studies of this condition. The present report deals with the cases of recent myocardial infarction in which electrocardiographic studies were made at the Michael Reese Hospital in the period from Jan. 1, 1940 to Dec. 31, 1945. Only the cases were included in which, on the basis of the history, the electrocardiograms and, when available, the observations at autopsy, the condition could unequivocally be diagnosed as a recent myocardial infarct. A total of 572 cases was selected. The patients for the most part were Jews; a few were Negroes. Of the total of 572 patients, 504 were admitted to the hospital for a six to eight week (rarely a ten week) stay as ward and private patients; on these, complete histories, serial