PURPOSE: The study was performed to examine postnatal growth curve for very low birth weight (VLBW) infants and to compare their catch-up growth in percentile with normal birth weight (NBW) infants. Also the role of various maternal and infant's factors that may predispose the VLBW infants for catch-up growth were evaluated. METHODS: The subjects for the study included 192 VLBW infants admitted to Asan Medical Center from January of 1997 to December of 1999. Of those 192 infants, a total of 113 infants were followed as an outpatient and their growth parameters including height, weight were obtained at each visit up to 18 months. We defined the catch-up growth as those who met 3rd percentile of normal Korean full term infant's growth curve. RESULTS: The results of the study showed that 3rd percentile mean body weight was attained by 18 months and 6 months in VLBW of less than 1,000 g and 1,000-1,499 g, respectively. The 3rd percentile mean height was attained by 18 months and 12 months for VLBW of less than 1,000 g and 1,000-1,499 g, respectively. Those infants of 1,000- 1,499 g attained 10th percentile weight and height by 15 months. The evaluation of the catch-up growth above 3rd percentile at various ages in month showed that weight attained above 3rd percentile were 42.5%, 73.5%, 80.5%, 87.6% and height attained above 3rd percentile were 33.6%, 75.2%, 89.4%, 92% at 6, 12, 15, 18 months, respectively. The result of logistic regression analysis of risk factors for catch-up growth at 12 months in VLBW infants revealed that gestational age and birth weight were important contributing factors. CONCLUSION: The 3rd percentile mean body weight and height were attained by 12 months in VLBW infants. Predisposing neonatal factors for catch-up growth included gestational age, birth weight, days of hospitalization, bronchopulmonary dysplasia (BPD), days of total parenteral nutrition and days of rehospitalization within 2 years after discharge from neonatal intensive care unit.