thalassemia is heterogeneous in severity however; the molecular basis of genotype-phenotype interaction is still unclear. The SNP analysis has revealed certain genes involved in apoptosis. Among these candidate genes, “Toso” was revealed to be the most significant. Toso is a cell surface protein, which functions as a negative regulator of Fas-mediated apoptosis. This protein has been reported to express hematopoietic cells. There is no evidence of toso expression in erythroid lineages. Therefore, the expression of toso in erythroid were studied. The result showed for the first time that toso was expressed in erythroid progenitors. The highest expression was found in orthochromatophilic erythroblasts. However, toso expression of erythroid cells at all stages of development demonstrated a low level. This was also confirmed by flow cytometry and Western blot. Thus it is possible that toso may express at a very low level or may not express in erythroid progenitors. The expression of toso in hematopoietic cells was further study in normal and thalassemia/Hb E patients. The results indicated that the expression level of normal and patients is not significantly different. Data analysis by Toso SNP genotpyes, RS94872 also showed not significantly different among each genotypes.