The aim of the study was to assess the trend of the infant mortality rate between 1990-2004 and the neonatal mortality between [2000][2001][2002][2003][2004][2005] in infants born at less than 32 weeks of gestational age or with very low birth-weight. Based on secondary data, infant mortality rate and by its component for Valdivia city were compared with national indicators. Mortality at <32 weeks and <1500g was calculated, establishing causes of death and evaluating its relation with specific interventions, such as the use of surfactant and antenatal corticoids.