Nine patients with atrial myxoma in whom selective coronary arteriography had been performed were studied. The angiographic sign of 'tumour vascularity' was found to be present in three patients with highly vascularized atrial myxoma. The clinical significance of the angiographic sign is unknown although highly vascularized myxomata appear to have a greater propensity to bleeding into the tumour, resulting in an acute worsening of clinical symptoms. The angiographic sign of 'tumour vascularity' is not specific but useful to complement the diagnosis of an atrial myxoma. The indication for selective coronary arteriography in patients with atrial myxoma remains the detection of coronary artery disease, thus concomitant coronary artery bypass surgery could be planned preoperatively.