The authors encountered 22 cases of congenital bicuspid aortic valve, some of which occurred in siblings. In this paper, a 58-year-old brother and a 56-year-old sister cardiac valve disease was diagnosed first at the age of 51 in the brother and at the age of 15 in the sister. Aortic valve replacement using a 21mm Medtronic-Hall prosthesis was done in both cases. Additionally, pacemaker implantation was carried out in the sister. Both cases showed favorable progress after operation. Hereditary factors are involved in congenital bicuspid aortic valve. Therefore if congenital bicuspid aortic valve are found in any patients, thorough investigations including cardiac auscultation, ECG and ultrasound cardiogram should be carried out routinely among immediate family members and relatives to reveal whether any of them is suffering from this congenital anomaly.