We herein present a case of a successful correction of cor triatriatum associated with thrombotic pulmonary hypertension diagnosed in an adult female patient. We confirmed diagnosis using transthoracic and transesophageal echocardiography in addition to cardiac computed tomography and magnetic resonance imaging. Surgical repair comprised excision of the fibromuscular membranous septum in the left atrium, patch closure of an atrial septal defect, and reconstruction of the pulmonary arteries with a vascular graft. Cor triatriatum complicated pulmonary thrombotic hypertension with atrial septal defect is amenable to surgical correction with satisfactory results.