Dynamic right ventricular outflow tract obstruction (RVOTO) has been reported following lung transplantation for pulmonary hypertension, usually in association with the use of inotropic agents. This report describes delayed severe right-sided heart failure associated with right ventricular outflow tract obstruction following sequential bilateral lung transplantation and closure of a ventricular septal defect. The patient had no evidence of outflow tract obstruction in the early posttransplant period but developed progressive right heart failure more than 2 months later. Catheterization revealed dynamic RVOTO and an elevated right ventricular end-diastolic pressure. The patient was treated with metoprolol tartrate and diltiazem hydrochloride with resolution of the outflow tract obstruction and heart failure. This case demonstrates that RVOTO can occur in the late posttransplant period and must be included in the differential diagnosis for patients who develop right-sided heart failure.