During the past 19 years, 229 autopsies of intracranial hemmorrhages were performed at the Department of Pathology, and 23 cases of posterior fossa subdural hemorrhages were discovered (10.0%). 25 cases of posterior fossa subdural hemorrhages (2 of our own treated surgically and 23 untreated found at autopsy) are described in detail. 2 cases treated surgically responded favorably to surgical treatment. The mechanism of hemorrhage into posterior fossa subdural spaces is investigated and reconsidered following a review of the literature. The necessity for CT is emphasized for early diagnosis of posterior fossa subdural hemorrhage.