In-utero treatment of fetal aortic stenosis (AS) may prevent hypoplastic left heart syndrome. A girl was diagnosed prenatally with severe AS and was referred to the Women's and Children's Hospital in Linz, Austria, where she underwent an intrauterine valvuloplasty of the aortic valve. Postnatally, the girl was given prostaglandin and operated a.m. Ross-Konno. An echocardiography at the age of four months showed a neoaorta without stenosis and insufficiency and a normal systolic function of the left ventricle. This treatment must be carefully considered when dealing with fetuses with AS.