ABSTRACT Background Lesions of the frontal sinus (FS) are always a surgical challenge. Conventional endonasal endoscopic techniques do not provide complete access inside the FS. This is especially true with laterally placed lesions like mucocele or post-traumatic cerebrospinal fluid (CSF) leak from FS. Standard procedures like osteoplastic flap and endoscopic modified Lothrop are not feasible for these smaller unilateral lesions with normally functioning contralateral sinus. Study design Retrospective case study of laterally placed posterior table CSF leak and frontal mucocele were evaluated for their clinical presentation, radiological, operative findings and follow-up. Conclusion Complete external approaches to the lateral lesion of FS are associated with high morbidity. Ability of the endoscopes to visualize lateral and posterior extents of the FS directly through the brow incision helps in complete repair/ excision of these lesions without any difficulty. How to cite this article Shanbag R, Bidkar V, Naik A, Jalisatgi R. Endoscope-assisted External Approach for Lateral Lesions in Frontal Sinus. Clin Rhinol An Int J 2013;6(2):72-76.