OBJECTIVE To provide growth charts for clinical monitoring of extra-uterine growth from birth to full-term age, in infants born before 26 weeks of gestation, hospitalized at neonatal intensive care unit (NICU), and compare it to the commonly used Swedish preterm birth-size reference. METHODS This retrospective longitudinal cohort comprised all infants born before 26 + 0 weeks of gestation and surviving to full-term age (n = 162), admitted to the NICU, Karolinska Hospital during the period January 1990 to December 2002. Body weight was recorded daily, head circumference (HC) weekly and length twice a month. RESULTS Birth weight (BW), length and HC showed a normal distribution without significant gender difference. The majority of the infants showed a pronounced postnatal growth restriction for all growth variables with increasing deviation from the reference with age. The mean initial weight loss was 16% with nadir at 6 days of age and a mean time to regain BW of 18 days. At discharge from NICU, 75% of those initially appropriate for gestational age infants were below -2 standard deviation scores for at least one of the body size variables. CONCLUSIONS The poor extra-uterine growth pattern points to the need of growth curves for extra-uterine growth of extremely premature infants.