We report on two patients in whom the anomalous left main coronary artery arising from the right sinus of Valsalva with a septal course could be visualized by transthoracic echocardiography. It appeared as a small echo-free space, anterior to the aorta in the short parasternal axis. If the left main coronary artery arises anomalously from the right sinus of Valsalva, it can take four different courses until it branches into the left anterior descending and the circumflex coronary artery. The course between aorta and pulmonary trunk can be differentiated into an interarterial and a septal course using angiographic criteria. The interarterial course is a potentially life-threatening anomaly due to a high rate of myocardial infarction and sudden cardiac death. Echocardiography alone seems not to be able to distinguish between the potentially life-threatening interarterial and the benign septal course, as in our patients.