Right ventricular (RV) outflow tract obstruction (RVOTO) is an uncommon complication of lung transplantation in patients with pulmonary hypertension (PH) and both medical management and surgical intervention are required. A 28-year-old female with primary PH was referred and because she did not respond to medical treatment, living-donor lobar lung transplantation was performed. The operation was successful, but dyspnea and exercise intolerance developed during rehabilitation and transthoracic echocardiography revealed RVOTO. Intravenous disopyramide during cardiac catheterization reduced the pressure gradient from 35 mmHg to 16 mmHg without decreasing RV systolic pressure. However, electrical and hemodynamic parameters were adversely affected by disopyramide and thus, after cardiac catheterization, administration of fluid and a low dose of atenolol was started, and her symptoms improved. Transthoracic echocardiography showed improvement in the RVOTO. This case suggests that disopyramide should be avoided for patients with RVOTO following lung transplantation and that other negative inotropic agents, such as beta-blockers, are more effective for relief of RVOTO.