In 1981, 151 neonates with birth weight (B.W.) less than or equal to 1500 g were admitted to the Port-Royal Intensive Care Unit (ICU) (31% of admissions), 81% being born outside. Total mortality was 26% (53% less than or equal to 1000 g). For children who died, the median hospital stay was 9 days; in survivors, it was 69d (109d for BW less than or equal to 1000 g 71d for BW 1001-1250 g, 61d for BW 1251-1500 g), similar in hypotrophic and eutrophic infants. Average weight at direct discharge from Port-Royal ICU was 2627 +/- 565 g. The smaller the infants were at birth, the later they were discharged after assumed term. Complications (more frequent in smaller infants) played a major part in discharge delay. The cost of initial care included every step from birth to final discharge, all hospital charges and transports. Average cost per survivor was 200,356 F, but it reached 336,545 F, in patients with bronchopulmonary dysplasia and 354,605 F in those with necrotizing enterocolitis. Although the mostly good quality of survival justifies these expenses, the authors advocate increased prevention of very early prematurity and severe intra-uterine growth retardation, and development of maternal transport, as well as of prenatal call for a neonatal team in cases of unexpected birth out a of a perinatal center.