Introduction. In iron overload status, excess iron deposits in reticuloendothelial cells and tissues and can be detected using Prussian blue staining. The aim of this paper was to investigate the relationship between siderocyte numbers and plasma ferritin levels (a practically standard marker of iron overload) in the blood of the splenectomized and nonsplenectomized β-thalassemia/HbE patients, who are at risk of iron overload. Methods. EDTA blood samples from 64 patients with 35 splenectomized and 29 nonsplenectomized β-thalassemia/HbE patients, who received regular blood transfusions, and 20 normal individuals were investigated for siderocyte numbers, plasma ferritin levels, and complete blood counts. Results. The average percent siderocytes in splenectomized and nonsplenectomized β-thalassemia/HbE patients were 11.5% and 0.08%, respectively, and plasma ferritin levels of 2,332 μg/L and 1,279 μg/L, respectively. Percent siderocytes showed a good correlation with plasma ferritin levels only in splenectomized patients (r = 0.69, P < 0.001). A receiver operating curve analysis from splenectomized patients' data indicated that siderocytes at 3% cut-off are the best predictor for plasma ferritin level ≥1,000 μg/L with 92.9% sensitivity and 42.9% specificity. Conclusion. Circulating siderocyte numbers can be used as a screening test for the assessment of the iron overload in splenectomized β-thalassemia/HbE patients in the place where serum ferritin is not available.