Since the introduction of microsurgical principles in the 1990s, the field of endodontic surgery has made continuous and substantial progress. Particularly, root-end cavity preparation has been simplified and optimized by means of newly developed surgical microinstruments. However, the successful outcome of endodontic surgery depends to a large extent on accurate intraoperative diagnostics. Conventionally, micromirrors (retromirrors) and microprobes have been used for this purpose. Recently, the surgical microscope has been used to enhance visibility during dental procedures. In addition, endoscopy has been reported to provide the surgeon with outstanding vision and ease of use. This article describes the technical specifications and the diagnostic application of the endoscope during endodontic surgery.