We report an unusual case of asymptomatic cor triatriatum found in a 30-year-old female suffering form Bechect's syndrome. Cor triatriatum was suspected from a routine echocardiography. The left atrium was divided into a posterior superior chamber and an anterior inferior chamber (true left atrium) by an echo-dense membrane. Two turbulent jet flows were demonstrated on transesophageal echocardiography. Catheterization and angiography demonstrated a mild increase in the pulmonary artery, and capillary wedge, pressures no associated anomalies, and with four pulmonary veins draining into the posterior chamber. The membrane was successfully resected by surgery.