PURPOSE: This study was undertaken to obtain the normative data on serum levels of IGF-I and IGFBP-3 in healthy Korean children and to evaluate the effects of age, sex, height, body mass index and pubertal maturation on the serum levels of IGF-I and IGFBP-3. METHODS: This study included 301 healthy Korean subjects in pediatric age group. Serum levels of IGF-I and IGFBP-3 were measured twice using IRMA kit in each individual. The correlations between the serum levels of IGF-I or IGFBP-3 and age, auxological data or children's Tanner stages were evaluated. RESULTS: Serum levels of IGF-I and IGFBP-3 increased in proportion to age progression, and their rates of increase were remarkable shortly before and during the puberty. The correlations between serum levels of IGF-1 and age, sex, height standard deviation scores, BMI, or pubertal maturation were significant(P<0.05). However, the serum levels of IGFBP-3 was correlated only with height standard deviation scores(P<0.05). There was a significant positive correlation between serum levels of IGF-1 and those of IGFBP-3(P<0.001). CONCLUSION: Although IGF-I and IGFBP-3 assays can be utilized for the evaluation of endogenous growth hormone status, the effects of age, sex, BMI, height and pubertal development on the levels of IGF-I and IGFBP-3 must be considered. Therefore, these results would be helpful as a normative data for the growth evaluation of children in Korea.