In the present study, we use diffusion tensor imaging (DTI) to detect acute white matter alterations in football players after sport-related concussion. DTI scans were performed on 30 male football players who had acute concussion (24-48 hours post-injury). Another 28 matched contact-sport players were recruited as controls. Mean diffusivity (MD) increased significantly in concussive group compared to the contact-control group. Long fibers including corpus callosum, corona radiata, and longitudinal fasciculus were more vulnerable than the rest of the brain white matter. Within the concussed group, axial diffusivity (AD) demonstrated positive correlation with symptom severity indicating potential axonal changes/damage.