In this study, protein C (PC), protein S (PS), heparin cofactor II (HCFII), prothrombin fragment 1+2(PF1,2), thrombin-antithrombin III complex (TAT), von Willebrand factor (vWF) and thrombomodulin (TM) were investigated in 13 patients with beta thalassemia intermedia (TI) not requiring transfusion, six patients with sickle cell disease (SCD), and seven patients with HbS-beta thalassemia (S-BT) who were not in crisis. These hemostatic parameters were also studied in 12 healthy children assigned as a control group. Protein C and Protein S (PC-PS) were found to be decreased in TI patients and normal in S-BT patients. PC was decreased in SCD patients. In the patients with TI and SCD, the mean PF1,2 level was elevated, whereas the TAT level was not statistically different from that of the control group. These results suggested that in patients with hemoglobinopathies: a) decreased natural anticoagulants and b) enhanced procoagulant activation have been encountered. Other unexpected and interesting results of this study are the decreased vWF and elevated HCFII levels in all three patient groups.