An 83-year-old woman with hypertension was admitted to hospital with episodes of dyspnea on effort after having breakfast. Physical examination revealed a systolic murmur at the left sternal border in the third to fourth intercostal space. Cross-sectional echocardiography showed a sigmoid-shaped interventricular septum markedly protruding into the left ventricle, concentric left ventricular hypertrophy, systolic anterior motion of the mitral valve, and a resultant left ventricular outflow tract obstruction with a pressure gradient of 121.8 mmHg. She began daily treatment with 60 mg metoprolol. However, the chest symptoms were not relieved and the left ventricular outflow tract obstruction was still visible on echocardiography. She was then given 200 mg daily of cibenzoline, in addition to 40 mg metoprolol, and the left ventricular pressure gradient significantly decreased and she was free of symptoms without any complications. This case shows that cibenzoline may be useful in the treatment of left ventricular outflow tract obstruction caused by sigmoid septum.