A patient with anomalous aortic origin of the left anterior descending coronary artery was studied. The clinical picture and the preliminary angiographic findings simulated obstruction of the left anterior descending coronary artery near its origin. Careful catheter exploration of the right coronary sinus led to the correct diagnosis, emphasizing the importance of complete visualization of all branches of the coronary tree, including distal radicles of a supposedly occluded vessel.