We describe two patients with cardiac tumors in the left atrium, which by their association and histopathological lineage, are extremely rare. The clinical, echocardiographic and pathological findings were analysed. The first case was asymptomatic, but in the control studies of colon adenocarcinoma, an intracardiac mass was found by chest computed tomography (CT). A transesophageal 3D (TEE 3D) echocardiogram revealed a left atrial mass attached to the interatrial septum. The mass was surgically removed and histopathologic findings showed myxoma. The second had history of chronic intermittent diarrhea. A thoraco-abdominal CT showed a left atrial mass. The TEE 3D echocardiography reported an intracardiac mass attached to the roof of the left atrium. The mass was surgically removed and the histopathogical findings showed a myxoma, with dystrophic ossification and extramedullary hematopoiesis. TEE 3D echocardiography provides an acceptable morphological characterisation of intracardiac masses, with good correlation with surgery.