The left atrial myxoma is a rare tumor in children. We describe a case of left atrial myxoma in a 6 year old girl discovered at the balance sheet of a recurrent cough. The presence of cardiomegaly on chest radiograph motivate a specialist consultation, the diminishing of which will be noted the presence of mitral insufficiency murmur intensity 3/6 auscultation and echocardiography mass ovoid, left atrial appendage, pendant to the septal wall, trained in the ventricle in diastole and systole annoying in the closure of the mitral valve, creating a mitral regurgitation grade 3 surgical resection will be conducted in France, with an absence of postoperative recurrence at two years.