In this case report, we describe a 67-year-old woman with right coronary artery-coronary sinus fistula. This woman had complaints of chest pain. Ischemic ECG changes and a ventricular tachycardia were detected on her electrocardiogram. Transthoracic echocardiography showed a large right coronary artery and a dilated coronary sinus. Drainage of the coronary artery to the coronary sinus was detected by colour flow mapping during transesophageal echocardiographic examination, and a 94 mmHg peak gradient was recorded by continuous wave Doppler at the drainage site. These findings were confirmed by cardiac catheterization. Transthoracic and transesophageal echocardiography can provide definitive confirmation of the right coronary artery-coronary sinus fistula, and can be the diagnostic procedure of choice when this anomaly is suspected.