Background: Diffusion tensor imaging (DTI) can be used to detect the accumulation of interstitial free water (FW) in the white matter of patients with cerebral small vessel disease (cSVD). Dynamic susceptibility contrast (DSC) imaging can be used to measure disruption of the blood-brain barrier (BBB). We hypothesized that regions of increased BBB disruption detected with DSC would show increased free water detected with DTI. Methods: A subset of patients enrolled in an ongoing study investigating the pathogenesis of cSVD were included. All patients had evidence of cSVD and a history of stroke >3 months prior to imaging. MRIs were performed with both DTI and DSC. White matter was segmented out from gray matter and CSF. FW was calculated from the DTI, and BBB permeability was calculated from aligned DSC. Regions of BBB disruption were grouped into 0.05% intervals ranging from 0-5%. For each echelon of BBB disruption, the average free water in that region was calculated for each patient. Mixed effects linear regression was used to test whether the degree of BBB disruption was associated with colocalized mean FW across all subjects while covarying for age and sex. Results: There were 11 subjects included in the analysis with a median age of 70, 45% were female. Increasing BBB disruption was associated with increased colocalized FW (beta = 0.13 [0.008 - 0.018], p < 0.0001). The figure shows a scatter of all data points with slopes fitted for each individual patient. Within subject linear regression of FW with BBB was significant for all patients and for the 9 patients with p<0.001, the R2 values ranged from 0.83 to 0.97 with a mean value of 0.91, suggesting that in most cases the FW increase is attributable largely to the disruption of the BBB. Conclusions: Disruption of the BBB leads to increased FW in the white matter of patients with cSVD. This proof of principle study demonstrates how these two biomarkers may be informative in when studying the pathogenesis of cSVD.