The echocardiographic aspects of the coronary sinus have not received much attention in the literature. In the few published articles about anomalous venous connection to the coronary sinus, the parasternal long axis view has been suggested as ideal for its visualization. More recently, it has been suggested that the coronary sinus in normal hearts is best visualized from the apical transducer position. The purpose of this study was to assess the appearance of the coronary sinus from an apical view in a group of 400 consecutive patients with ages varying from 5 days to 80 years. In ten patients with persistent left superior vena cava, the coronary sinus was markedly dilated throughout its extension. All cases were confirmed either by angiography or surgery. In another three patients with Ebstein's anomaly studied postoperatively, it was observed that the coronary sinus was abnormally draining into the right ventricle below the prosthesis plane. These findings were confirmed by the surgical reports. The routine evaluation of the coronary sinus was better performed by an apical view, which provided detailed information not only of normal, but also abnormal anatomy of this segment of the heart. We speculate that it could be especially useful in diagnosing coronary sinus atresia and thrombosis, and coronary ostium atresia, as well as total anomalous intracardiac pulmonary venous drainage.