Iron is an essential component in the structure of certain molecules such as hemoglobin (Hb), myoglobin, cytochrome C and some enzymes. The iron gateway to cells is transferrin receptor (TfR). Soluble transferrin receptor (sTfR) is a product of the TfR that circulates in plasma, its concentration therefore, is proportional to the total concentration of cellular TfR. Expression of TfR is elevated in anemia. The aim of this study was to evaluate the efficacy of sTfR determination in the diagnosis of iron deficiency in thalassemia carriers. In this cross-sectional study, 168 cases were examined. The subdivision of cases included: iron deficiency, concurrent thalassemia and iron deficiency, severe α-thalassemia (α-thal) (α-thal-1), mild α-thal (α-thal-2) and β-thal minor. Hematological and biochemical variables were analyzed by the Statistical Package for Social Sciences (SPSS) version 16 statistical software. Analysis of variance was carried out using the non parametric Kruskal-Wallis test. Significant differences were observed in median values in sTfR concentration and sTfR/log ferritin (sTfR-F index) iron deficient groups, compared to thalassemia groups (p value <0.001), with both variables having higher values in iron deficient groups. In this study it was demonstrated that in iron deficient thalassemic patients, high sTfR can be a good indicator of iron deficiency anemia. The result of the sTfR test can be used for calculation of the sTfR-log ferritin index (sTfR-F index) (obtained by division of sTfR into log ferritin). This is a more sensitive parameter for iron deficiency diagnosis because in its calculation, two valuable amounts of sTfR and ferritin were taken into consideration.