Severe coronary arteriosclerosis has been produced in female rats (a) bred repeatedly, (b) subjected to unilateral nephrectomy, and (c) treated with ACTH. The coronary lesions in these animals resemble those seen in man. Morphologically, the coronary arteriopathy is varied, i.e., intimal hyperplasia, deposition of basophilic material in intimal and medial layers (possibly acid mucopolysaccharides), elastosis, and mural swelling leading to complete obliteration of the lumen. Coronary and mural thrombi occur frequently. No fat or salt is added to the diet. Serum cholesterol levels are normal. The possible role of "stress" in induction of this type of coronary artery disease has been discussed.