BACKGROUND The distribution of hemoglobin (Hb) levels and the prevalence of anemia are significant public health indicators. The aims of this study were to determine the distribution of Hb levels and the prevalence of anemia according to sex, age group, and region throughout Korea. METHODS The study analyzed data on 1 159 298 subjects who received health checkups at 16 health-promotion centers in 13 Korean cities during 2018. Anemia and its severity were defined according to the World Health Organization classification for Hb levels as follows: mild anemia (11-12.9 g/dL in males and 11-11.9 g/dL in females), moderate anemia (10-10.9 g/dL in both sexes), and severe anemia (<10.0 g/dL in both sexes). RESULTS The Hb level in the general sample was lower in females (13.25 ± 1.13 g/dL, mean ± SD) than in males (15.29 ± 1.22 g/dL). The overall prevalence of anemia was 6.0% (2.98% in males and 8.56% in females), and the prevalence of severe anemia was 0.92% (0.23% in males and 1.51% in females). While the prevalence of anemia increased monotonically with age in males, it was bimodal in females with two peaks at 40-49 years and ≥80 years. The highest prevalence of anemia in females aged 40-49 years was attributed to microcytic anemia, while increases in anemia prevalence in males aged ≥50 years and females aged ≥70 years were attributed to macrocytic anemia. CONCLUSIONS The distribution of Hb levels and the prevalence of anemia overall and by severity differ according to sex, age group, and region throughout Korea.