A case of cor triatriatum in a 66-year-old man is reported. The patient died of pneumonia; ante mortem diagnosis was made with both transthoracic and transesophageal echocardiography. Autopsy finding showed a very good correlation between anatomical and echocardiographic abnormalities. Cor triatriatum is amenable to surgical correction and echocardiography is extremely helpful in the diagnosis.