Two patients with metastatic tumors invading the left atrium are described. One is a 52-year-old woman with osteosarcoma; the other is a 77-year-old man with lung cancer. The first patient presented with severe dyspnea 1 year after treatment for a primary tumor. Cardiac metastasis was suspected, then documented by transesophageal echocardiography. The study of pulmonary vein flow showed decreased systolic forward and increased diastolic components of pulmonary venous flow. The second patient presented with chronic cough without dyspnea. Although a huge tumor invaded the left atrium, as in the first patient, a normal pattern of pulmonary vein flow with higher systolic than diastolic velocities was shown by transesophageal echocardiography. Thus, transesophageal echocardiography is not only a useful tool to diagnose left atrial metastatic tumors, but also the study of pulmonary venous flow patterns can delineate causes of dyspnea in patients with metastatic tumors invading the left atrium.