The first endoscope was conceived as early as 1806. Since then successive technical advances led endoscopy of the nose and paranasal sinuses to a routine procedure. From the rediscovery of the rigid telescopes by Hopkins in the fifties, progress has stemmed essentially from the quality of the more powerful cold lights and the improvement in the light output of the fiber optics. Exam procedures of the nose and sinuses are conducted under general as well as local anesthesia, and are commonly combined with concomitant diagnostic procedures: measure of the mucociliary clearance with indicators, biopsies, smear sampling for bacterial and fungal examinations, and sinusomanometry which can help to estimate the patency of the maxillary ostium and of the nasofrontal duct. Sinus endoscopy has been widely used to correlate efficiency of other diagnostic techniques such as plain X-rays, CT scanners, A and B mode ultrasonography. A similar work should be done for MRI. Endoscopic exploration is the key to the management of chronic pathology as it brings precise information on the quality of the naso-sinus mucosa, the presence of secretions and, combined with sinusomanometry, the functional state of the ostia or ducts.