Pituitary apoplexy usually presented with abrupt onset of neurological deterioration of headache, visual disturbance and decreased mental status. Post-traumatic pituitary apoplexy generally occurs in patients who have suffered from severe head injury, but there are rare reports occurred in patients with mild head injury. We describe a rare case of atypical presentation of acute pituitary apoplexy following mild head injury. A 68-year-old woman presented with right parietal scalp swelling after minor head trauma. Glasgow Coma Scale (GCS) score was 14. Initial computed tomography (CT) scans showed multiple contusions in the basal forebrain, falx hemorrhage and a linear skull fracture near the midline. In addition, there was a suprasellar-extended pituitary macroadenoma with suspicious intratumoral hemorrhage. After admission, cloudy consciousness, poor oral intake and high fever continued for several days. On seventh day, her condition has abruptly deteriorated and hypotensive shock developed. She recovered dramatically two days after steroid replacement therapy. The mechanism of pituitary apoplexy after mild head injury discussed with a relevant literature.