Orbital swelling in children presents diagnostic and therapeutic challenges. Most are associated with acute sinusitis with complicating factors possibly including: amaurosis, meningitis, intracranial abscess or even cavernous sinus thrombosis. However not all acute orbital swelling is associated with acute sinusitis. A careful evaluation is critical prior to initiating therapy. Clinical records of 49 children (27 girls, 22 boys, with an average age of 11.8 years) were retrospectively reviewed. Historical data evaluated included all available information from parents and previous treating physicians. All patients underwent intensive pediatric, ophthalmologic, and otorhinolaryngologic examinations. Computed tomography (CT scans) were additionally performed in 40 % of children. The results of any examinations were also evaluated. Eighteen of the 49 patients had an orbital complication due to acute sinusitis. All 18 had elevated body temperature, C-Reactive Protein (CRP) values and white blood cell counts. Endoscopy of the nose revealed pus in the middle meatus in each case. According to Chandlers' classification, ten children presented with a preseptal, and eight children had a postseptal orbital cellulitis. All patients were admitted to the hospital and treated with intravenous antibiotics. CT scans further demonstrated signs of subperiostal abscess in four children. Functional endoscopic sinus surgery (FESS) was required in six children, including all patients with subperiostal abscess. Twenty children experienced orbital swelling unrelated to acute sinusitis, i.e. atheroma, inflammed insect stings, dental related abscess, conjunctivitis, and Herpes simplex associated superinfection. In three children, acute orbital swelling was caused by an orbital tumor. Orbital complications of an acute sinusitis occur often in the pediatric patient group, and most of these patients can be treated conservative with intravenous antibiotics. Indications for FESS include failure to improve or worsening of clinical symptoms during 24 h of therapy, signs for subperiostal abscess in CT scan, and/or vision loss. Patients with infectous orbital complications had fever, elevated CRP and white blood cell counts. This symptom complex is key in making the correct diagnosis. Interestingly, 61 % of patients in this study demonstrated non-sinusitis related diseases leading to acute orbital swelling, which also required prompt recognition and appropriate therapy.