BACKGROUND. Regular blood donation can lead to pre-clinical iron deficiency as well as iron deficiency anemia. With Each donation donors lose 220-250 mg of iron. Early detection of iron deficiency is important for the blood donors and even useful for blood and blood product safety and supply. The research work we studied present Ret-HE to be used to detect the occurrence of iron deficiency eritrony level. Purpose: The aim of this study was to determine Ret-He to have sensitivity and specificity for diagnosing iron deficiency than traditional iron measurements. Materials and methods: We performed a cross sectional and case control study of 156 blood donors who served National Center for Transfusion Medicine. Ret-He, hemoglobin, plasma iron and ferritin were measured using XN2000 Sysmex, and CobasE600 Roche. The statistical analysis was done using One way Anova, Rock curve, Kruskal Wallis test. Results: We examined 64(41.02%) male donors, 92(58.9%) female donors by measurements of Ret-He,hemoglobin, serum, iron and ferritin. Survey participants were 8.33%(n=13) with anemia, 91.67% (n=143) without anemia. In donors with anemia the results were: RBC 4.9*106 u/l, HGB 10.8 g/dl (10;11), serum ferritin 5.2 (4.3; 6.3) mmol, serum iron 4.5 (3.7; 5.8) mmol and Ret-He 25.5 (22; 26) pg. Donors were divided into 3 age groups: group I age was up to 25years, group II was between 26-35 years, group III age criteria was above 35. Group I had serum iron 13.5 (10.; 18.), serum ferritin 41.8 (14; 78), Ret-He 32.2 (30; 33.) RBC 5×106 u/l (4.6;5), HGB14.2g/dl (13.3;14. 2). Group II had serum iron 14.6 (11; 19), serum ferritin 54.1 μg/l (29; 138), Ret-He 32.2pg (31; 33), RBC 5.1×106 u/l(4.7;5.1), HGB14.8 g/dl (13.5;14.8),Group III had serum iron 15.1 umol/l (9; 20), serum ferritin 95.7 μg/l (39; 141), Ret-He 32.7pg (31; 34) , RBC4.9×106 u/l(4.6;4.9), HGB 14.5g/dl(13.8;14.5), respectively. According to a curve (Roc) analysis, AUC of serum iron was 0.0963, serum ferritin 0.909, Ret-He 0.975. The mean Ret-He was 32.3pg (31.3;33.4). The optimal cut off value for the Ret-He was 29,25pg by ROC analysis and are presented along with sensitivity 92.3% and specificity 95.1%. Conclusion: 1. Determining the amount of Ret-He has a better sensitivity and specificity for diagnosing iron deficiency compared to traditional iron measurements. 2. Ret-He has diagnostic indicators that are able to detect the depletion of iron reserves, erythron level. And it need to be used in further clinical practices, as well as doctors should be required to use it for diagnosis and treatment.