Real-time three-dimensional echocardiography can surpass simple cross-sectional echocardiography in providing precise details of cardiac lesions. For the purpose of optimising treatment, we describe our findings with real-time three-dimensional echocardiography when interrogating different types of communications permitting interatrial shunting. A three-dimensional reconstruction of defects within the oval fossa enabled reliable identification of location, size, and integrity of surrounding rims. In the superior sinus venosus defect associated with partially anomalous pulmonary venous drainage, three-dimensional reconstruction helped to provide a better understanding of the relationship between the interatrial communication, the orifice of the superior caval vein, and the connections of the right upper pulmonary vein. In the defect opening infero-posteriorly within the oval fossa, three-dimensional reconstruction helped to avoid the risk of potentially inappropriate closure of the defect by suturing the hyperplastic Eustachian valve to the atrial wall, which could have diverted the inferior caval venous return into the left atrium, or obstructed the caval venous orifice. In the coronary sinus defect, three-dimensional echocardiography provided a ‘face to face’ view of the entire coronary sinus roof, showing a circular defect communicating with the cavity of the left atrium. Acquisition of the full-volume data sets took less than 2 minutes for the patients having defects within the oval fossa, and no more than 3 minutes for the patients with the sinus venosus and coronary sinus defects. Post-processing for the defects in the oval fossa took from 5 to 8 minutes, and from 12 to 16 minutes for the more complicated defects.