Three patients developed hemorrhage in the splenium of the corpus callosum 2 weeks after the onset of subarachnoid hemorrhage (SAH) associated with acute hydrocephalus. Computed tomography performed a few days after the onset showed a low density area in the splenium of corpus callosum in all three patients, and preventive measures against symptomatic vasospasm were begun, including vasodilator administration. Computed tomography showed hemorrhage in the splenium of the corpus callosum 17 to 22 days after onset of SAH, manifesting as mental deterioration or headache. Antivasospasm agents were immediately discontinued, and strict blood control measures were instituted. Splenial hematoma is another potential cause of neurological deterioration after surgery for SAH, in addition to vasospasm, hydrocephalus, and rebleeding.