This paper describes an endoscopic transseptal approach to identify and access the frontal sinus and reviews the clinical cases. Between May 2004 and July 2010, endoscopic modified Lothrop procedure (EMLP) with transseptal approach was performed on sixteen patients. The indications for EMLP were complicated frontal sinusitis or cyst, revision surgery for failed frontal sinusotomy or Lynch procedure, or trauma cases. The first step of this procedure was to open a window in the bilateral anterior portion of the middle turbinates and nasal septum. The nasal septum, which could be observed through the window, should be the landmark of the midline during the surgery. A drill bur was raised up just behind the nasal bone along the midline of the nose. After the bilateral frontal sinuses and their posterior walls were confirmed, the interfrontal septum was removed superiorly. We reviewed the clinical records of patients who underwent the EMLP with transseptal approach. We have managed sixteen patients in this fashion. Neither intracranial nor orbital complications were encountered during or after surgery.Endoscopic transseptal frontal sinus surgery is simple to perform, and does not cause severe complications.