A 36-year-old woman was admitted because of an enlarged right heart. Echocardiographic examination revealed an abnormal vessel connecting to the dilated coronary sinus. The abnormal vessel traveled in the direction from the right axillary to the left epigastric region. Partial anomalous pulmonary venous connection (PAPVC) from the right upper lobe to the coronary sinus was initially considered as a possible diagnosis by echocardiography. At surgery, diagnosis of an isolated PAPVC of the right upper pulmonary vein to the coronary sinus was confirmed.