Morbility and mortality among 121 infants with birth weights less than 1.500 grams born during year 1982 were studied. Jaundice was present in 54,6% of the cases and was followed in incidence by metabolic problems (hypoglicemia, hypocalcemia, late metabolic acidosis) and respiratory distress syndrome. Forty seven infants survived (39%). There were no survivors when birth weight was less than 750 grams. Survival rates were respectively, 23,6%for infants weighting 751 to 1.000 grams: 40%between 1.001 and 1.250 grams and 63,3% between 1.250 and 1.500 grams. The principal causes of death were extreme prematurity, respiratory distress syndrome and intracraneal bleeding. This type of study is necessary in Neonatal Units to plan adecuate resources and to get the best possible results.