A mass with a diameter of 0.8 cm was detected in the aortic root of a 53 year old woman during routine preoperative cross sectional echocardiographic assessment of a secundum atrial septal defect. Intraoperative epicardial echocardiography showed that the mass was attached by a slender stalk to the tip of the left coronary cusp of the aortic valve, and histological examination showed that it was a papillary tumour. Intraoperative epicardial echocardiography can help in planning the excision of papillary tumours, and excision is advised even when there are no symptoms.