Abstract : Nosocomial infections (NI) remain a major problem of public health, giving rise to a serious morbi-mortality and significant costs. They represent a consequence of the medical progress and of the misuse of broad-spectrum antibiotics. Obviously, premature newborn of low birth weight present an increased risk of NI related to their degree of immaturity,as well as the invasive procedures use, and long-lasting hospitalizations.. Epidemiological data concerning NI in neonatology remain imprecise due to diagnostic difficulties. Responsible germs are related to the territory and its local ecology. Bacterial NI are the most frequent even if viral and Candida NI are widely underestimated and gradually gain ground.The medical and economic consequences of these infections justify prevention measures such as prematurity prevention and management of pregnancy taking into account the NI risk. Finally, simple measures such as a strict hygiene in newborn care and the limitation of invasive procedures in terms of frequency and duration have to be a priority.