alpha-Hemoglobin stabilizing protein (AHSP) is an abundant, erythroid-specific protein that forms a stable complex with free alpha-hemoglobin but not with beta-hemoglobin or hemoglobin A. As such, AHSP is required for normal erythropoiesis, probably acting by blocking the deleterious effects of free alpha-hemoglobin precipitation. In order to study the levels of expression of the AHSP gene during the different phases of erythropoiesis, we carried out a two-phase liquid culture of erythroid cells and real-time quantitative polymerase chain reaction. Blood from control volunteers was cultured with erythropoietin to stimulate differentiation. The different stages of erythropoiesis were confirmed by morphologic and flow cytometric analysis. The results showed a progressive increase in AHSP gene expression following the expression of alpha-globin gene, during maturation of the red blood cell precursors, confirming the probable important function of this protein during normal erythropoiesis.