Results are presented on epidemiologic surveillance of nosocomial infection of all neonates attended at the Instituto Nacional de Perinatologia throughout 1988-1990, reporting rates of 2.1, 2.9 and 5.5 per 100 discharge for each of the years studied. Data are presented in full by service, showing rates of 4.7, 9.5 and 23.0 per 100 discharge in Neonatal Intensive Care Unit (NICU) and 1.5, 3.2 and 6.7 per 100 discharge for Neonatal Intermediate Care (NIC) for the same three years. With respect to type of infection, septicemia, pneumonia and conjunctivitis come as the most frequent causes of infection and Staphylococcus sp coagulase negative (30%), Staphylococcus aureus (27%) and Escherichia coli (7%) as the prevailing microorganisms in nosocomial infection.