Posterior reversible encephalopathy syndrome (PRES) has been described in the setting of malignant hypertension, renal disease, eclampsia, and immunosuppression. In addition, a single case of intraoperative (posterior fossa craniotomy) PRES has been reported; however, this case occurred in an adult. The authors present a clinically and radiographically documented case of intraoperative PRES complicating the resection of a posterior fossa tumor in a 6-year-old child. During tumor resection, untoward force was used to circumferentially dissect the tumor, and excessive manipulation of the brainstem led to severe hypertension for a 10-minute period. An immediate postoperative MR image was obtained to rule out residual tumor, but instead the image showed findings consistent with PRES. Moreover, the patient's postoperative clinical findings were consistent with PRES. Aggressive postoperative management of blood pressure and the institution of anticonvulsant therapy were undertaken. The patient made a good recovery; however, he required a temporary tracheostomy and tube feedings for prolonged lower cranial nerve dysfunction. Posterior reversible encephalopathy syndrome can occur as a result of severe hypertension during surgery, even among young children. With prompt treatment, the patient in the featured case experienced significant clinical and radiographic recovery.