Background and Objectives: In newborns and infants during their first year of life, there is a dynamic change in the fraction of hemoglobin (Hb). To apply Hb analysis as a phenotypic diagnosis of thalassemia in newborns and infants, we need normal values of each Hb fraction for reference. Methods: Seventeen cord bloods from normal deliveries were collected for analysis. One hundred and thirty seven infants from the pediatric outpatient clinic were recruited and were categorized by their ages into a series of short periods (month+2 weeks). Both alpha and beta thalassemia carriers detected were excluded. Samples with an Hb level less than 10.0 g/dL were also excluded. The proportion of Hb A (a2b2), A2 (a2d2), and F (a2g2) was obtained from high performance liquid chromatography and analyzed according to its categorized periods. Results: There were 90 (58.4%) specimens left for evaluation. The percentage of Hb A, A2, and F gradually changed with increasing age. The percentage of Hb A was 21.14+7.04% (mean+SD) in cord blood and increased substantially to 83.38+1.31% at the sixth month. The level was sustained thereafter. The incremental pattern of Hb A2 was similar to Hb A. The value was 0.32+0.19% at the beginning and reached a plateau with 2.78+0.25% at the sixth month. The percentage of Hb F started at 78.39+7.59% in cord blood and decreased rapidly in the first 6 months. Conclusions: The data possibly can be applied as quick guidance for interpretation of Hb analysis in newborns and infants during their first year of life.