A 33-year-old female patient with advanced idiopathic pulmonary artery hypertension underwent bilateral lung transplantation. The postsurgical course was complicated by prolonged mechanical ventilation and acute hypoxemia with recurrent episodes of pulmonary edema. An echocardiogram revealed improved right-sided pressures along with a dilated left atrium, a structurally normal mitral valve, and a new posterior-oriented severe mitral regurgitation. The patient's condition improved after treatment with arterial vasodilators and diuretics, and she has remained in World Health Organization functional class I after almost 36 months of follow-up. We hypothesize that cardiac ventricle remodeling and a geometric change in mitral valve apparatus after transplantation led to the hemodynamic changes and recurrent pulmonary edema seen in our patient. Our case is, to our knowledge, the second report of severe valvular regurgitation in a structurally normal mitral valve apparatus in the postoperative period and the first of a patient to be treated without valve replacement.