The pathology of aortic valve diseases can manifest at subvalvular, valvular, or supravalvular level. Fetal supravalvular aortic stenosis is very rare, while subvalvular stenosis is encountered more often in the setting of complex congenital defect. The most common fetal aortic valve diseases are represented by atresia or valvular stenosis. This is often characterized by restricted cusps excursion and post-stenotic dilatation of the ascending aorta. In aortic atresia an imperforate membrane is guarding the aortic severe hypoplastic annulus and ascending aorta. The blood flow and pressure reduction on the left side of the heart during gestation impact on the remodeling cardiac process leading to hypoplastic left heart syndrome.