We selected a paediatric population with a high risk of nosocomial infection formed by 116 newborns (42.8%) and 155 not newborns (57.2%) admitted into the ICU of the Giannina Gaslini Institute during the period 1-1-1992-30-9-1992; we compared it with a reference paediatric population studied in the same department during the period 1-1-1987-30-6-1988 formed by 310 newborns (44.3%) and 391 not newborns (55.7%). The purpose of this study is to evaluate the possible change in the incidence of colonizations and ICU specific nosocomial infections, the possible increase of nosocomial infections by multiresistant Staphylococci and the appearance of new multiresistant germs. The two populations obviously present similar factors of high risk of nosocomial infection (naso-tracheal intubation, mechanical ventilation, total parenteral nutrition, surgical procedures, thoracic and/or abdominal prothesis, etc.). The obtained data have been examined with the Chi-square method. The incidence of colonizations remained unchanged while we noted a significant increase (10.3% compared to 4.9%-p > 0.0014) of the "ICU" specific nosocomial infections; the increase regarded mainly the neonatal population (18.9% compared to 7%-p > 0.00001). Significant increase of the nosocomial infections by multiresistant Staphylococcus (Staphylococcus haemolyticus) with in vitro and in vivo resistance to teicoplanin. Furthermore, presence in the performed study of multiresistant gram negative germs.