The capability of non-enhanced and enhanced CT scanning of the heart without ECG gating to detect myocardial infarction in living dogs was explored. CT findings were correlated with those at post mortem. In large transmural infarctions, areas of lower attenuation were detected without contrast medium enhancement and appeared as defects when intravenous contrast medium was administered. The infarct size as estimated on each CT scan correlated closely with post mortem values.