A posterior reversible encephalopathy syndrome (PRES) is characterized as headache, altered mental function, seizure, and visual disturbances resulted from vasogenic edema in the brain. A 29-year-old normotensive parturient developed a postural headache two days after the cesarean section under spinal anesthesia. The headache was initially misdiagnosed as a postdural puncture headache (PDPH). The patient experienced generalized seizures four days after delivery. Her blood pressure increased to 170/100 mmHg with mild proteinuria. She developed homonymous hemianopsia two days after the seizures. MRI revealed high signal intensity areas in the posterior temporal, frontal, occipital and parietal white matter. Presuming a diagnosis of PRES, the patient was treated with magnesium sulfate, sodium valproate, and carbohydrate solutions. She was discharged without headache or neurologic deficit on postoperative day 13. When patients present a headache with focal neurological deficits or visual disturbances, the anesthesiologist must consider the possibility of PRES and aggressively treat based on the clinical presentation.