Acute rhinosinusitis is frequently associated with secondary orbital infection, most commonly subperiosteal abscess. Although orbital subperiosteal abscess is a deadly disease that might lead to blind and cavernous sinus thrombosis, recent review of literature showed that immediate surgical intervention might not always be necessary for subperiosteal abscess. Orbital inflammation secondary to sinusitis is common in children, whereas orbital subperiosteal hematoma secondary to sinusitis is extremely rare, with only 11 reported cases, including one case in children. All the cases were treated with surgical intervention. Here we present a 12-year-old girl with rhinosinusitis and proptosis. Emergent endoscopic sinus surgery with partial removal of the lamina papyracea revealed dark brown fluid in the subperiosteal space. The patient was symptom-free 2 weeks after surgery. The present case was treated exclusively via an endonasal approach, whereas all 11 previous cases of subperiosteal hematoma were treated with external incision. The endonasal approach is favorable, especially for young female patients. Our review of literature shows that sudden onset, afebrile, and few signs of inflammation on blood test in patients with subperiosteal lesion may indicate subperiosteal hematoma. Surgery rather than antibiotic administration should be considered for the treatment of suspected subperiosteal hematoma. Treatment through only the endonasal approach is possible even if the hematoma is located in the roof of the orbit.