Transesophageal echocardiography (TEE) is a useful modality for imaging cardiac masses. Atrial myxomas account for 90% of all cardiac tumors found at operation, and 50% of tumors found at autopsy. Pericardial cysts are frequently asymptomatic and may be an incidental finding. Mediastinal cysts, including bronchogenic and duplication cysts, may occur. These have a more echodense appearance on TEE, and may contain thicker mucilaginous material that may layer differently with postural change. Cardiac tamponade may be defined as the decompensated phase of cardiac compression resulting from increased intrapericardial pressure. Constrictive pericarditis is characterized by a fibrotic, inflamed, or calcified pericardial sac. In patients with a suspected cardiac mass, transesophageal echocardiography is recommended for determining its nature, and the assessment of sources of cardiac embolism. It may be particularly useful in patients with loculated or trapped pericardial fluid, for example in the post-operative setting.