Subdural hematoma can cause compression or damage to the neural tracts in the brain;however,very little is known about this injury.We report on a patient with subdural hematoma who was evaluated by diffusion tensor imaging prior to and after trephination and drainage of subdural hematoma.A 58-year-old male patient and ten age-matched normal control subjects were evaluated.The patient showed mild hemiparesis for 3 weeks prior to surgery.His hemiparesis recovered to a nearly normal state at 5 weeks post-surgery when the follow up diffusion tensor image was acquired.Two diffusion tensor image parameters,fractional anisotropy and apparent diffusion coefficient,were measured along the corticospinal tract.Pre-operative diffusion tensor image showed that the corticospinal tract of the affected hemisphere seemed to be injured or compressed.However,the follow up diffusion tensor image showed recovery of this corticospinal tract to a normal state.It would appear that diffusion tensor images are a useful tool for evaluation of the effects of subdural hematomas on neural tracts.