The Authors describe a new case of monosomy 9 p in a newborn, confirmed by bands technique. The parents had a normal karyotypes and this alteration was defined as deletion 9 p "de novo" arisen. The main morphological anomalies are described: these anomalies reproduce that reported by others and, for many aspects, remember Down syndrome. It is very important that the staff of the Neonatological Departments has a good knowledge of this syndrome since for the abnormal objective features, the diagnosis is possible already from the birth.