We evaluated echocardiographic accuracy for defining coronary artery course in d-transposition of great arteries and the impact of a 2-reviewer method on this accuracy. The echocardiogram reports of 108 patients with d-transposition of great arteries were reviewed for coronary anatomy and compared with the operative report. In method 1, from January 1995 to December 1997, a single reader performed the echocardiogram. In method 2, from January 1998 to December 2000, 2 readers scanned individually and a consensus diagnosis was made. Comparing methods 1 and 2, the sensitivity of the echocardiogram to detect variants in coronary anatomy was 68% versus 86%, and negative predictive value was 72% versus 91%. Using a 2-reviewer method improved the accuracy of echocardiographic diagnosis of coronary anatomy with d-transposition of great arteries, aiding in risk assessment and treatment of the patient preoperatively. This study also illustrates that echocardiographic accuracy may be lower in an institution with a surgical volume more representative of the usual pediatric cardiothoracic surgical center.