Both two-dimensional transthoracic echocardiography (2DTTE) and live/real time three-dimensional transthoracic echocardiography (3DTTE) were attempted in a 25-year-old morbidly obese female with total anomalous pulmonary venous return (TAPVR) into the coronary sinus (CS) in whom surgical unroofing of CS with patch closure of CS ostium was performed in infancy to redirect pulmonary venous flow into the left atrium (LA). The patient had become increasingly symptomatic over the past 1 year because of severe left-to-right shunting due to dehiscence of the patch used to close the CS ostium. Despite a poor acoustic window, 3DTTE was able to identify a communication between the LA and CS which resulted from surgical unroofing of the CS as well as flow signals moving into the right atrium from the CS. These findings were not detected by 2DTTE. © 2007, the Authors.