We surveyed computed tomographic findings after 1074 intracranial operations to determine the incidence and etiology of postoperative intracerebral hemorrhages. Medium or large hemorrhages occurred after 42 operations (3.9%). Larger hemorrhages, hemorrhages in the suprasellar region, and hemorrhages associated with other types often preceded a poor outcome. Major etiologies underlying postoperative intracerebral hemorrhages were uncontrolled bleeding from a blind area, difficult dissection of a tumor from the brain, retraction injury, vessel injury from a needle, bleeding from a residual tumor, local hemodynamic changes after removal of a tumor, premature rupture of an aneurysm, and hypertensive putaminal hemorrhage. Hypertension during recovery from anesthesia was another important factor.