Visual field defect is one of the various clinical manifestations in patients with subarachnoid hemorrhage (SAH). Little is known about the pathogenic mechanism of visual field defect in SAH. In the current study, we investigated the diffusion tensor imaging (DTI) finding of the optic radiation in patients with SAH fol-lowing rupture of a cerebral artery aneurysm. We recruited 21 patients with aneurismal SAH (12 males, 9 females, mean age, 52.67 years; range, 41-68 years) who showed no definite lesion along the visual pathway. Twenty-one age-and sex-matched normal control subjects were also recruited. DTI data were acquired at an average of 5.9 weeks (range: 3-12 weeks) after onset and reconstruction of the optic radiation was per-formed using DTI-Studio software. The fractional anisotropy value, apparent diffusion coefficient value, and fiber number of the optic radiation were measured. The fractional anisotropy value of the optic radia-tion was significantly decreased, and the apparent diffusion coefficient value was significantly increased, in patients with aneurismal SAH than in normal control subjects. However, there was no significant differ-ence in the fiber number of the optic radiation between patients with aneurismal SAH and normal control subjects. The decrement of fractional anisotropy value and increment of apparent diffusion coefficient value of the optic radiation in patients with aneurismal SAH suggest optic radiation injury. Therefore, we recommend a thorough evaluation for optic radiation injury in patient with aneurismal SAH.