Chronic cerebrospinal venous insufficiency (CCSVI) is a vascular picture that shows a strong association with multiple sclerosis (MS). The aim of this study was to investigate the relationship between a Doppler cerebral venous hemodynamic insufficiency severity score (VHISS) and cerebrospinal fluid (CSF) flow dynamics in 16 patients presenting with CCSVI and relapsing-remitting MS (CCSVI-MS) and in eight healthy controls (HCs). The two groups (patients and controls) were evaluated using validated echo-Doppler and advanced 3T-MRI CSF flow measures. Compared with the HCs, the CCSVI-MS patients showed a significantly lower net CSF flow (p=0.027) which was highly associated with the VHISS (r=0.8280, r2=0.6855; p=0.0001). This study demonstrates that venous outflow disturbances in the form of CCSVI significantly impact on CSF pathophysiology in patients with MS.