A 41-yr-old woman with pulmonary carcinoid tumour presented for thoracotomy and lung resection. However, intraoperative transoesophageal echocardiography (TEE) revealed that the tumour had invaded the left atrium, and the planned resection was aborted to allow resection under cardiopulmonary bypass at a later date. Although the incidence of cardiac involvement by lung cancer at the time of pulmonary resection is unknown, transoesophageal echocardiography can be useful in identifying the extension of hilar lung tumours. This should preferentially be done preoperatively, but can be done intraoperatively as described in this case report.