OBJECTIVE Pediatric idiopathic orbital inflammation (IOI) is a rare entity with little known about the clinical presentation and natural history. The authors report the demographics, clinical presentations, radiographic and histopathologic characteristics, and treatment outcome of 30 children with IOI. METHODS Retrospective chart review of 30 patients 18 years and younger diagnosed with IOI and statistical analysis using analysis of variance and Fisher's exact test. This study was reviewed and approved by the Institutional Review Board of SUNY Downstate Medical Center. RESULTS There were 9 males (30%) and 21 females (70%) with pediatric IOI who presented at a median age of 11 years (range 2-18 years). Primary IOI was found in 19 patients (63%) and recurrent IOI in 11 patients (37%). Overall, 26 patients (87%) had unilateral IOI while 4 patients (13%) had bilateral disease at presentation. There were 12 patients (40%) with systemic constitutional signs. The most common ophthalmic findings included periorbital edema (n = 20, 67%) and blepharoptosis (n = 17, 57%). All patients had orbital radiography with common findings of dacryoadenitis (n = 12, 40%), orbital mass (n = 12, 40%), or myositis (n=10, 33%). The presence of a radiographic orbital mass was significantly related to the clinical presence of blepharoptosis (p = 0.03). The most common treatment was oral glucocorticoids in 24 patients (80%). Over mean follow up of 19 months (range 6-64 months), females were more likely to display recurrent disease (p = 0.01). CONCLUSIONS Idiopathic orbital inflammation is an uncommon but important cause of acute orbital syndrome in children, manifesting as a bilateral condition in 13% and with constitutional symptoms in 40%. Posttreatment recurrence is found in 37% of cases.