BACKGROUND Growth hormone (GH), insulinlike growth factor-1 (IGF-1), and IGF-binding protein-3 (IGFBP-3) are used in the neonatal period for evaluation of diseases such as GH deficiency, intrauterine growth restriction, and hypoglycemia. However, GH level has been reported as a single value during the neonatal period. In this study, we attempted to determine the changes of GH, IGF-1, and IGFBP-3 in the neonatal period for each week. METHODS One hundred and two appropriate-for-gestational age (AGA) term neonates who did not have any diseases that would interfere with GH-IGF axis were included in this cross-sectional study. Blood samples were collected and serum GH, IGF-1 and IGFBP-3 levels were measured by immunoradiometric analysis (IRMA) and weekly values were obtained for the first postnatal four weeks. RESULTS We showed that GH level [median (1st-3rd quartile)] decreases from the first to the fourth postnatal week [25.1 (18.5-37.4); 17.2 (13.2-22.8); 17.6 (12.2-20.2); 14.4 (6.60-19.8) ng/mL, respectively)], IGF-1 and IGFBP-3 levels [median (lst-3rd quartile)] increase [41.7 (18.0-70.0); 55.9 (39.0-103); 53.0 (40.0-97.7); 71.7 (44.3-137) and 1852 (1597-2451); 2430 (1645-2838); 2841 (2280-3675); 3018 (2151-4189) ng/mL, respectively)]. CONCLUSIONS GH, IGF-1 and IGFBP-3 values can be evaluated for each week separately instead of for the entire neonatal period.