Ischemic myocardial injury has been detected recently in isolated perfused hearts and intact experimental animals with positron-emitting 11C-palmitate and reconstructive tomography providing cross-sectional images of the heart free from superimposed activity in overlying structures. To evaluate the applicability of positron emission transaxial tomography in detecting infarction in man, 10 normal human subjects and 12 patients who sustained documented acute myocardial infarction three to 12 months previously were studied. Tomograms were obtained after intravenous injection of 5 to 10 mCi of 11C-labelled palmitate, a physiological substrate of myocardium. Tomograms from all normal subjects exhibited homogeneous distribution of 11C-palmitate throughout each 1.5 cm thick cross section of the ventricle. Tomograms from all patients with remote anterior or inferior and posterior myocardial infarction exhibited diminished accumulation of 11C-palmitate delineating regions corresponding to the electrocardiographic locus of infarction. The distribution of 11C-palmitate detectable by positron emission transaxial tomography in a series of cross sections from apex to base in the same normal subject or patient with remote myocardial infarction was analogous to that observed in normal dogs and animals with experimentally induced myocardial infarction.