Chronic subdural hematomas (cSDH), a common condition tends to develop several weeks after head trauma in patients with atrophic brains, such as the elderly. Arachnoid cysts (AC) are congenital intracranial lesions filled with cerebrospinal fluid (CSF). They have a benign natural history in most patients, and are often found incidentally on intracranial images performed after head trauma. On rare occasions, ACs are complicated by cSDHs. Herein, we present a case involving a patient with AC-associated cSDH.