Three hearts with transposition of the great arteries had an aberrant coronary artery coursing between the aortic and pulmonary roots. This coronary artery remained embedded in the aortic wall for some distance. In each case, on external inspection, the abnormal artery presented as a separate vessel at the site from which it usually originates in the left sinus of Valsalva. Internal inspection showed that in two cases the aberrant coronary orifice was in the posterior sinus, intimately related to the commissure between the left and posterior sinuses. In the third case the orifice was in an ectopic high position above this commissure. Diagnostic and surgical implications of this rare coronary arterial configuration are discussed.