Computed tomographic (CT) equipment capable of high-resolution, rapid-sequence scanning allows detection of intracardiac and intrapericardial masses. Two patients with intrapericardial masses (pheochromocytoma, organized hematoma) and three patients with intracardiac masses (right ventricular rhabdomyosarcoma, right atrial metastasis, and left atrial thrombus) are presented. CT is the imaging method of choice for displaying pericardial masses directly and may be superior to echocardiography and angiocardiography in the detection of ventricular thrombi. In patients with cardiac tumors, CT evaluates extent of disease including invasion of contiguous vessels and pulmonary metastases better than echocardiography. Dynamic scanning after bolus intravenous injection of contrast material is recommended for the evaluation of patients with suspected masses involving the heart or pericardium.