The author reports on a concept, developed over a 10-year experience with 1,080 patients, for treating chronic pansinus disease by an endonasal micro- and endoscopic technique, either alone or in combination with an external (osteoplastic) approach. He describes techniques and indications for simple drainage, extended drainage, or medium drainage of the frontal sinus. Patients who have already undergone several frontal sinus procedures can be treated definitively by combining a procedure using a transfrontal external approach (osteoplastic procedure) with fat obliteration of the frontal sinus, and endonasal micro-endoscopic ethmoidectomy. Because of inflammatory orbital periostitis, subperiosteal abscess, orbital phlegmon, or intracranial complications (meningitis, encephalitis), the endonasal micro-endoscopic approach was used to operate on 47 of 389 patients who underwent procedures for simple, extended, or median drainage of the frontal sinus. The author reports on a concept, developed over a 10-year experience with 1,080 patients, for treating chronic pansinus disease by an endonasal micro- and endoscopic technique, either alone or in combination with an external (osteoplastic) approach. He describes techniques and indications for simple drainage, extended drainage, or medium drainage of the frontal sinus. Patients who have already undergone several frontal sinus procedures can be treated definitively by combining a procedure using a transfrontal external approach (osteoplastic procedure) with fat obliteration of the frontal sinus, and endonasal micro-endoscopic ethmoidectomy. Because of inflammatory orbital periostitis, subperiosteal abscess, orbital phlegmon, or intracranial complications (meningitis, encephalitis), the endonasal micro-endoscopic approach was used to operate on 47 of 389 patients who underwent procedures for simple, extended, or median drainage of the frontal sinus.