Cardiac tumors account for 0.2% and can either be primary of metastatic (secondary), the latter being 20 to 40 times more frequent than the primary ones. When it comes to primary tumors, 75% are benign and approximately 50-85% of those represent myxomas, with an incidence of 0.5-1 in 106 individuals per year. We present the case of a 56 year-old patient, without cardiovascular risk factors or pathological history, with a 4.6 × 4.5 cm left atrial myxoma prolapsing into the mitral valve during diastole causing an intermittent obstruction and severe mitral valve stenosis. Diagnosis was reached with a transthoracic echocardiogram without need of further diagnostic tests. Surgical resection was performed, achieving complete resection of the tumor. Patient's evolution was satisfactory, he was discharged 11 days after the surgery.