Severe maxillofacial trauma accompanied by a dislocated ethmoidal bone fracture was confirmed by CT imaging in 15 adult patients. Routine surgical management included reduction of fractures, miniplate fixation and/or intermaxillary fixation with interosseous wiring. The fractured ethmoidal cell system was left to heal spontaneously. A follow-up examination including endoscopy of the nasal cavity as well as active anterior rhinomanometry and computed tomography was carried out approximately 24 months after surgery. The fractured ethmoidal cell system showed a clear tendency to spontaneously reventilate and drain. However, in 8 of 30 sides a traumatic obstruction of the anterior ethmoid led to secondary frontal sinus mucositis. 12 out of 30 maxillary sinuses ranged from marked mucosal swelling to the development of a traumatic mucocele. Altogether, 9 of the 15 patients suffered from paranasal sinusitis. Routine debridement of every fractured ethmoidal cell system does not appear to be necessary. In case of fractures of the anterior ethmoid with probable obstruction of the nasofrontal duct and/or maxillary sinus ostium, endonasal endoscopic surgery is recommended for minimally invasive reconstruction of the ventilation and drainage of the frontal and maxillary sinus during primary surgical management. Furthermore, patients with severe naso-orbito-ethmoidal fractures should undergo rhinological follow-up examination including CT-imaging approximately 3 months after surgery.