Measurable myocardial infarcts of predictable size and location were produced in dogs by low ligation of the left descending coronary artery just proximal to the origin of the apical branch. Two groups of dogs with such infarcts were studied, one group being treated intramuscularly with two daily closes of 20 units of Acthar Gel for 9 to 11 days and the other group being untreated. At the end of the experimental period there was no demonstrable difference between the two groups with respect to the size, site or histologic appearance of the infarcts.