Background and Aims: There are possibilities of insufficiency in blood flow through carotid arteries during head positioning in thyroid surgeries under general anesthesia which is usually compensated by collateral circulation in normal conditions. This compensation may be hampered in patients with congenital abnormalities or diseases such as atherosclerosis. We aimed to elucidate the changes in common carotid artery blood flow related to head positioning during thyroid surgery by Doppler examination. Methods: In this observational prospective study, Doppler examination of both common carotid arteries including arterial diameter, peak systolic velocity, average velocity, and blood flow volume of forty patients who had undergone elective thyroidectomy under endotracheal anesthesia was done. Three sets of data (baseline, after induction, and after surgery) were collected and analyzed. Results: There was a significant reduction in the diameter ( P = 0.002) and the blood flow ( P = 0.0001) in both carotid arteries and an increase in peak and mean velocity which was more pronounced immediately after head positioning and persisted till the end of the procedure. There was no correlation between the hemodynamic parameters with the carotid artery diameter, blood flow, and velocity. Conclusions: The head-and-neck positioning during thyroidectomy surgery reduces the blood flow through the carotid arteries which continued till the end of the procedure.