This study was peformed to evaluate the clinical symptoms and treatment results in children with orbital subperiosteal abscess. We retrospectively analyzed medical record and computed tomographic image in 17 children with orbital subperiosteal abscess. We divided the patients into two groups: the medication group and the surgery group that underwent transnasal endoscopic ethmoidectomy and abscess drainage in addition to medication. Mean age was 10.2+/-4.9 years and 13 patients (76.5%) were male. Clinically, periorbital swelling was detected in all patients. Proptosis and ocular motility limitation were developed in 13 patients (76.5%). Mean time to improvement was 8.7 (5 ? 16) days, and mean hospitalization duration was 8.5 (5 ? 15) days. Mean time to improvement in patients who underwent transnasal endoscopic ethmoidectomy (4.4 days) was shorter than in those treated medically (1.3 days) (p<0.05). All patients were resolved without recurrence or complications during more than 3 months of the follow-up period. In children, orbital subperiosteal abscess can be cured by prompt diagnosis and appropriate antibiotics medication or surgery. Endoscopic ethmoidectomy can significantly reduce the time required to improvement.