Pseudoaneurysms of the heart have a propensity to rupture and surgery is indicated. Usually in these cases diagnostic imaging is based on angiographic and/or echocardiographic studies. We have attempted to determine in pre- and postoperative studies the value of CT and ECG-gated MRI in patients with pseudoaneurysm. Seven patients with a pseudoaneurysm and/or dyskinesia of the posterolateral or diaphragmatic wall of the left ventricle were investigated with CT and/or ECG-gated MR studies, in addition to angiography, echocardiography, and radionuclide studies, prior to cardiac surgery. Postoperative follow-up studies with CT in six and MR in five patients were also carried out. Both CT and ECG-gated MRI allowed us to visualize the neck and CT also confirmed the communication between the cavities with or without demonstrating the conduit. In addition, disruption of the epicardial fat layer by the pseudoaneurysm was seen on both CT and MR, and the presence of intrapericardial adhesions was visualized on MR. Finally, CT and MRI, in postoperative follow-up studies, may indicate a myocardial discontinuity adjacent to the surgical patch.