Orbital complications of sinusitis represent serious diseases. In clinical practice, the term "orbital phlegmon" is often used, although this most serious expression of orbital infection is very rarely seen. However, a correct classification in each stage of orbital complications and resulting treatment recommendations are crucial for the prognosis of the patient. Data from 49 patients who underwent treatment for orbital complications from 01/01/2000 until 31/12/2010 were retrospectively analysed. In particular, data on the epidemiology, diagnostic procedures and treatment methods were analyzed. From the observation period 109 patient records with the diagnosis "orbital affections" (ICD-10 H05) could be identified. Overall, data from 49 patients (36 male and 13 female) with orbital complications of sinusitis could be analyzed. 53.1% of the patient population were children and adolescents aged 1-20 years. Orbital complications were classified using the classification according to Chandler. The group I and II according to Chandler emerged most frequently. 26 patients (53.1%) showed a preseptal cellulitis (group I) and 11 patients (22.4%) had an orbital cellulitis (group II). Patients from group III or higher according to Chandler received a combined medical and surgical treatment. Orbital complications of sinusitis mostly seem to arise in infancy and adolescence. With prompt identification of the orbital complications in stage I and II of Chandler, conservative therapy only could be successful. From the third stage up, sinus surgery needs to be considered. The classification of Chandler allows a correct recommendation of therapy.