Diagnosis of anomalous origin of the right coronary artery from the pulmonary artery by echocardiography, Abstract Purpose To review the imaging characteristics and evaluate the diagnostic value of echocardiography for diagnosing anomalous origin of the right coronary artery from the pulmonary artery (ARCAPA). Methods We retrospectively reviewed the echocardiographic records and compared these images with operative findings in six children with ARCAPA. Results ARCAPA was characterized by dilation of the left coronary artery, inappropriate origin of the right coronary artery from the pulmonary artery, and collaterals within the interventricular septum. The associated malformations included atrial septal defect in four cases. Four of six cases were diagnosed correctly, while the remaining two cases were misdiagnosed: one of fistula between the pulmonary artery and the left coronary artery and another of ARCAPA diagnosed intraoperatively in one case of atrial septal defect. Conclusion ARCAPA can be diagnosed by echocardiography but is prone to misdiagnosis. This malformation should be distinguished from coronary artery fistula.