Although extensive experimental studies have been made of the effects of ligation of the coronary arteries, apparently no review of the effects of exercise following experimental cardiac infarction has been made. Knowledge of the effects of exercise at varying intervals after ligation should give information that could be transferred to the treatment of human beings. Accordingly a series of experimentally produced infarcts in dogs was studied as to the effects of regulated exercise. Kolster1 observed dogs living seventeen months after ligation of the ramus descendens anterior. Miller and Matthews2 kept dogs alive for ninety days after ligation of the left coronary artery. Both described infarcts, and Miller and Matthews2 observed marked thinning of the ventricular musculature near the apex. Smith3 observed the electrocardiographic changes following ligation of the ramus descendens anterior in dogs living up to sixty-three days. He is the first author to mention the