Multiplanar reformatting was combined with electrocardiographically gated computed tomography (CT) to provide a three-dimensional assessment of the beating heart of a live dog. Separate systolic and diastolic images were made in transverse, sagittal, coronal, and paraxial views. Three-dimensional contour images that outlined the cardiac chambers and the myocardium were then made using a separate research computer. This three-dimensional appreciation of cardiac morphology could be extended to assess regional function. Practical problems that limit the application of these methods are discussed, along with the proposed solutions.