The findings on computer tomography after ligation of the coronary artery of a dogs heart are described. The ischaemic area can be differentiated from normal myocardium by its hypo-dense appearance. The localisation and size of the ischaemic area correlates with the scintigraphic findings. The known morphological and functional changes after intravenous oxyfedrin (positively inotropic, increased myocardial blood-flow) can also be seen on the computer tomogram (after oxyfedrin: myocardial thickening, reduction in cross-sectional area of the left ventricle, improved contraction, increased density of the ischaemic area). This confirms the possible diagnostic role of CT in the elucidation of changes in the left ventricle in the course of coronary disease.