Background. Hematologic reference values vary by ethnicity. We aimed to determine reference values of hemoglobin (Hb) for Korean children and adolescents. Methods. Using data from the 5th Korean National Health and Nutrition Examination Survey (KNHANES), we obtained reference values for Hb in children and adolescents aged 10-20 years. Results. Among 2,526 subjects recruited, 330 were excluded due to chronic diseases (9 congenital heart disease, 6 epilepsy, 1 thyroid disease) or abnormal laboratory values (253 subjects with Fe/TIBC 16%, 103 subjects with MCV 80 fL). Accordingly, data from 2,196 subjects (male=1,196, female=1,000) were analyzed and age- and gender-stratified means and percentile values of Hb were obtained. Peculiar findings observed in the current study were: (1) Hb levels in Korean male were similar to those of non-Hispanic Caucasians; (2) Hb values in females were similar to those of non-Hispanic Caucasians until age of 15, and thereafter were slightly lower. Prevalence of anemia according to WHO criteria and our own criteria (Hb levels 2 standard deviations of age- and gender-specific values) in total sample was 3.5% (88/2,526) and 3.8% (97/2,526), respectively. Anemia was more prevalent in female in comparison with male (6.5% vs. 1.0%, P0.001). Conclusion. Our results could be used as a national reference standard to correctly classify a large population sample. Further studies are necessary to determine reference Hb values for children younger than 10 years and identify genetic variations associated with distinctive characteristics observed in this study.