A 73-year-old woman with a history of atrial fibrillation suffered from exertional chest pain and discrete dyspnoea. Cardiac catherization showed a vascular malformation in the atria, fed from vessels of the circumflex and left descending coronary artery. Echocardiography detected a biatrial tumour (13.7 x 9.7 cm). The tumour mass was completely removed and histologic examination revealed a biatrial myxoma with extensive vascular lesions which apparently induced angina by coronary steal effect.