In 16 dogs, a selective myocardial infarction (MI) was experimentally provoked without open-chest-surgery by means of microspheres (MS) injected into a Judkins-catheter positioned into the left anterior descending coronary (LAD) under fluoroscopy. This was shown by ECG-abnormalities, increase of the serum-enzymes of myocardial necrosis, decrease of left ventricular end diastolic pressure (LVEDP), wedge pressure, and cardiac output. After 5 weeks, thoracotomy showed a myocardial infarction limited to the anterior wall of the heart, which was of subendocardial location and consisted of multiple zones of microinfarction. Histological examination of the corresponding area showed necrosis of myocardial muscle fibres.