This study describes two cases of the rare congenital anomaly, persistent fifth aortic arch. Both cases involve boys (1 at 9 years of age and another at 7 months of age). To detect persistent fifth aortic arch with interrupted aortic arch, the following methods were used: echocardiogram, angiocardiography, and magnetic resonance imaging. In both cases the blood pressure between the upper and lower limbs differed. To relieve the obstruction of blood flow, each case was surgically repaired using patching or conduit interposition. Postoperative courses were uneventful. Two-year to 5-year follow-up examinations were positive showing that the anastomosis was unobstructed and the velocity of blood flow to the descending aorta was normal.