This study investigated relationships among quantified white matter hyperintensity (WMH) volumes and core cognitive skills in long-term survivors of childhood posterior fossa tumor utilizing a novel automated neuroimaging approach. Thirty-five survivors and 56 healthy controls underwent MRI and neuropsychological testing. Results indicated that log transformed normalized total WMH volumes differentiated groups based on treatment type, where survivors treated with chemoradiation therapy had significantly higher volumes of total WMH compared to survivors with surgery only and healthy controls, and survivors with surgery only had higher WMH volumes than healthy controls. In the total sample, higher total WMH volumes were associated with poorer performance on all cognitive measures. Three types of analyses indicated varying results about relationships among WMH location and oral processing speed. The most robust analysis, multivariate regression, showed periventricular WMHs are related to oral processing speed performance.