Background:Posterior chronic subdural hematomas (pCSHs) are rare. Their diagnosis and treatment are difficult.Description:A 69-year-old woman was admitted to our hospital with nausea, headache, and mild consciousness disturbance. Computed tomography and magnetic resonance imaging showed bilateral pCSH. To prevent further neurological deterioration, we performed surgery under general anesthesia by midline suboccipital craniectomy. Unexpected bleeding from a developed circuitous occipital sinus was stopped with hemoclips. After hematoma removal, she recovered and was transferred to a rehabilitation hospital. By the 19th postoperative day, she had developed no neurologic deficits.Conclusion:This experience demonstrates the risk of blind surgical therapy in patients with pCSH. In such patients, posterior fossa craniectomy may be preferable in terms of diagnosis and safe treatment.