The pathophysiology, clinical presentation and prognosis of left ventricular obstruction present an important cardiological problem. Various anatomical and functional abnormality can cause this phenomenon. Rarely, left ventricular outflow obstruction can result after mitral valve surgery. We experienced a case of left ventricular outflow obdtruction 13 years after mitral valve replavement. The diagnosis was made using two-dimensinal Doppler echocardiography and confirmed by cardiac catheterization. The pressure gradient across the left ventricular outflow obstruction was 96mmHg. A second mitral valve replacement was performed. Because severe fibrosis, pannis around the prosthetic mitral valve and a subaortic web were detected during the operation, the subaortic web was removes.