Hypoplasia of the left heart is a spectrum and choice of surgical treatment is difficult for some cases. The echocardiography of a 13-day-old girl revealed hypoplasia of the left ventricle, mitral valve, transverse aorta and isthmus. The interventricular septum was intact and the aortic valve was bicuspid. The gradients at the level of coarctation and aortic valve were 30.5 mmHg and 15.7 mmHg respectively. There was no retrograde flow in the ascending aorta. Biventricular versus univentricular repair was discussed. Considering Z scores of the left heart structures, balloon coarctation angioplasty was performed. The dimensions of the left ventricle increased in follow-up. Among the suggested echocardiographic measurements, z score of the mitral valve annulus, the direction of the flow in the ascending and transverse aorta maybe more predictive in determining the hypoplastic left hearts that would potentially grow. Balloon anjioplasty provides time before definitive surgery. Copyright © 2011 by Türkiye Klinikleri.