The aim of this study was to investigate the flow volumes of the internal jugular veins (IJVs) in patients with cerebral venous sinus thrombosis (CVST) using Doppler ultrasonography (DUS) and to compare the findings with the control group. Forty patients diagnosed with CVST between 2008 and 2010 were included in the study. The patients diagnosed with a thrombosis via MRV and MRI underwent a bilateral examination of the IJVs by DUS. The patients were divided into three groups: Group I (n=29) unilateral total thrombosis; Group II (n=6) bilateral diffuse thrombosis; and Group III (n=5) unilateral partial thrombosis. The IJV flow volumes of each group were compared to that of the control group (n=20). In Group I, the average flow volume was 53 ml/min on the side of the thrombosis. In Group II, the mean volume of the right and left IJV was 265 ml/min, and in Group III, the mean volume on the side of the partial thrombosis was 160 ml/min. The flow volume on the thrombosed side in Group I and Group III and the mean of the total bilateral flow volume in Group II were significantly lower than that of the control group. IJV flow volumes in the CVST group were significantly lower compared to the control group. Reduced flow volumes of the IJV may be diagnostic for CVST or an additional parameter to be considered with the use of MRI.