The surgical treatment of the CoAo plus Hypoplastic Aortic Arch is debated. The point is whether to treat or not the associated tubular hypoplasia performing an extended Resection and "End to End" Anastomosis (ERETE) or a subclavian flap angioplasty (Waldhausen). According to some report in the literature we called an arch hypoplastic if its diameter in the first or second portion was less than the patient body weight plus 1. Between January 1988 and December 1992 in our Institution 38 patients less than 3 months underwent aortic coarctation repair. In 14 cases we were able to consider the aortic arch as hypoplastic. These patients were aged between 3 days and 45 days (median 15 days), the body weight was between 2.6 and 3.9 kgs (median 3.2 kgs). 6 patients had CoAo as isolated lesion, in 3 cases there was Ventricular Septal Defect (VSD) associated. In 5 patients major intracardiac anomalies were associated (1 DORV, 1 TGA, 2 SV, 1 SV+Arterio-Ventricular discordance). In 7 cases in order to treat the arch an ERETE was performed. The other 7 patients had a Waldhausen procedure. In 5 cases a Pulmonary Artery Banding (PAB) was associated, in 1 case a palliative arterial switch operation. The hospital death was 43% (3 patients) in the ERETE group, and 28% (2 patients) in the Waldhausen group. The echocardiography and or angiography performed during the follow-up period showed a nice growth of the arch in both groups. Although from our present data it's impossible to get definitive conclusions, the ERETE doesn't give better result in terms of hospital death and long term aortic arch growth.(ABSTRACT TRUNCATED AT 250 WORDS)