A study of 1,915 patients operated on with a total of 4,285 endoscopic endonasal ethmoidal procedures during a period of 18 years is presented. The study comprises five groups of patients with (1) acute recurrent and chronic sinusitis--long-standing symptoms >3 months--(n = 733), (2) nasal/paranasal polyposis (n = 710), (3) sinogenic headache (n = 325), (4) mucoceles (n = 59) and (5) other nasal/paranasal disorders (n = 88). This group includes acute sinus infection with complications (n = 38), acute trauma/injury (n = 22), Grave's disease with exophthalmus (n = 12) and olfactory dysfunction (n = 16). The need for a thorough examination leading to a final diagnosis is emphasized. Endoscopy and CT/MRI are standard tools in the diagnostic and postoperative process. Close cooperation and educational teaching of the patient are necessary to obtain highest compliance. Long-standing medical treatment of inflammatory diseases is important to the long-term outcome and is of utmost importance to surgical success. Surgery is recommended to be performed under general anesthesia (total intravenous anesthesia or laryngeal mask anesthesia) with additional local, topical anesthetics, and can be easily performed on a day-case out-patient basis. The surgery is based upon the Messerklinger technique (MT). Peroperative complications are reduced by a skilled and meticulous surgical conduct and an adequate medication preoperatively. During this period of time, necessary controls within the first postoperative month were reduced from 3-4 to only one. Long-term follow-up secures a long-standing optimal result. Endoscopic surgery for more rare conditions, such as orbital decompression, CSF leaks and meningoceles, is recommended to be performed in specialized centers with adequate trained staff and necessary equipment. The possibilities of the picture archiving communication system, giving a number of different projections and angles and video-guided imaging peroperatively, facilitates safe surgical performances in areas usually associated with great risks and hazards. The long-term results are very good during the above circumstances. Reoperations are few and the patient satisfaction is very high.