Introduction: Determination of hemoglobins (Hbs) F, A 2, and E is crucial for diagnosis of thalassemia. This study determined the levels of Hbs F, A 2, and E in children aged 6-23 months and investigated the effect of age, sex, and types of thalassemia on the expression of these Hbs.Methods: A total of 698 blood samples of Laotian children including 272 non-Hb E, 271 Hb E heterozygotes, and 155 Hb E homozygotes were collected. Hb profiles were determined using the capillary zone electrophoresis. Coinheritance of α-thalassemia and the homozygosity for Hb E mutation were checked by PCR-based assay.Results: Children heterozygous and homozygous for Hb E had significantly higher Hb F and A 2 levels than non-Hb E children (median Hb F = 1.1% for non-Hb E group, 2.7% for Hb E heterozygotes, and 9.4% for Hb E homozygotes; median Hb A 2 = 2.6% for non-Hb E group, 3.8% for Hb E heterozygotes, and 5.2% for Hb E homozygotes).The median Hb E levels were 21.9% for Hb E heterozygotes and 85.3% for Hb E homozygotes. Comparing within group, there was a statistically significant difference between children with and without an α-gene defect for Hb A 2 and E, but not Hb F.Based on a multiple regression analysis, age and sex were significantly associated with the expression of Hb F and A 2 but not Hb E. Conclusions:Our findings can guide the development of a diagnostic approach to thalassemia in children aged 6-23 months.