The object of this study was to determine whether the hospital stay could be reduced in low birth weight infants without any risk. A prospective, controlled and randomized study has been made with 80 newborn infants with birth weights < or = 2.000 gm. The infants of the experimental group (n = 40) were discharged with weights < or = 2.000 gm and the control group (n = 40) were discharged with weights > or = 2.000 gm. Both groups showed similar social, economic, perinatal and postnatal conditions. We have found significant advantages in the experimental group such as: reducing the period of hospitalization (p = 0.005), greater weight increase (p < 0.001), a longer breast feeding period (p = 0.02) and a 29% reduction in expenditures. The follow-up shows that there are no significant differences between the groups regarding morbidity, mortality, growth or psychomotor development. We conclude that there are no disadvantages, but considerable advantages, in early discharge of low birth weight infants.