OBJECTIVE The objective of this study was to analyze the weight, length and head circumference development in prematurely born babies who weighed less than 1,500 grams and who were included in the follow-up program of our neonatal unit. METHODS Review of data of the cohort included in the follow-up program between May 1990 and September 1995 was carried out. The weight and length were measured from 3 months of corrected age to 4 years of age. The head circumference was measured until 2 years of age. RESULTS We recruited 259 premature newborns (136 boys and 123 girls). The median gestational age was 30 weeks (23 to 36) and the median weight was 1,150 g (500 to 1,499 g). Twenty-seven percent were underweight for their gestational age (LWGA). The proportion of cases with weight below the 3rd percentile in the follow-up was stable around 25% in the group of adequate weight for gestational age. (AWGA). At 3 months of corrected age this proportion was 70% in the LWGA group, but there was a trend towards catch-up at 2 years of age. The worst results were obtained in the group that weighed less than 750 g at birth. The head circumference was better preserved than longitudinal growth and thus better than weight. All cases of head circumference below the 3rd percentile in the follow-up occurs in the LWGA group. CONCLUSIONS Weight was the parameter with the worst evolution during follow-up, especially in the group that weighed less than 750 g at birth. The group of LWGA tended to catch-up at 2 years of age.