Abstract: The aim of this study was to determine the percentage of RBCs vesicles in the peripheral blood of β-thalassemic patients, using flow cytometry and study its relationship to the degree of severity of anemia. Thirty one β-thalassemic patients and 23, age and sex matched healthy controls were included in this study. All patients and controls were subjected to full history taking, complete clinical examination, complete blood picture, hemoglobin electrophoresis and estimation of RBCs vesicles percentage, by flow cytometry technique. We reported that RBCs vesicles were present in both normal and thalassemic blood samples, but their percentage was significantly higher in the β-thalassemia group as compared with the control group (p = 0.002). Also, the percentage of circulating RBCs vesicles was significantly higher in splenectomized thalassemic patients as compared with non-splenectomized cases (p = 0.041) and with controls (p = 0.001). No correlation was found between RBCs vesicles percentage and clinical or haematological data of β-thalassemia. From that study we concluded that flow cytometric determination of RBCs vesicles percentage is simple, reliable and may offer new insights in the assessment of possible thrombotic complications in patients with thalassemia.