To assess the secular trend in length of hospital stay for healthy newborns with birth weight >or= 2,500 g in a large maternity hospital of Campinas, state of São Paulo, Brazil. In this descriptive, analytical, retrospective study, data were collected from 5,001 live births from 1951 to 2000. Studied variables were length of hospital stay, birth weight, maternal age, type of delivery, and category of admission. Linear regression analysis was used, with least squares estimation. The annual mean length of stay decreased along the period assessed: 123 hours in 1951 and 67.2 hours in 2000. Segmented linear regression analysis revealed a significant decreasing trend between 1951 and 1970, a stable period between 1971 and 1990, and a non-significant increase between 1991 and 2000. Length of hospital stay varied significantly according to type of delivery. Length of hospital stay decreased significantly between 1951 and 2000 and was influenced by type of delivery only.85175-8