OBJECTIVE: Patients with hemoglobinopathy are prone to cerebrovascular event. Our aim was to screen the peak systolic flow velocity (PSV) using transcranial Doppler ultrasonography (TCD) in terms of cerebrovascular event risk in patients with beta thalassemia (ß-thal) and sickle cell anemia (SCA). METHODS: PSV and resistive index (RI) values were determined at internal carotid artery (ICA) and middle cerebral artery (MCA)-from both temporal regions using TCD. RESULTS: A total of 55 participants (40 patients and 15 healthy people) were included in the study. Thirty-three (60%) of the participants were female. Among 40 patients, 12 patients (30%) had NTDT, 14 patients (35%) had SCA, and 14 patients (35%) had TDT diagnosis. Bilateral ICA and MCA were open in all patients and had a normal flow pattern. PSV and RI were not significantly different between study and control groups in right and left MCA and ICA. Patients with high platelet level (>450.000/mm3) had significantly higher PSV values in right MCA (96 vs.70 cm/s, p=0.05). Among patients with TDT, age of starting iron chelation and right ICA PSV values was significantly negatively correlated (r=-0.56; p=0.04). Clinical symptoms (headache and pain crisis), hydroxyurea, and chelation therapy did not effect PSV values. CONCLUSION: Platelet level and age of starting iron chelation might be an influencing factor for PSV. Regular follow-up of patients, appropriate therapy and lack of other factors causing cerebrovascular events might be possible reason for these acceptable results. [ABSTRACT FROM AUTHOR]