This chapter discusses endoscopic sinus surgery for chronic rhinosinusitis (CRS), which is an inflammatory disorder of the nose and paranasal sinuses of multifactorial, incompletely elucidated etiology and great individual and societal impact. The mutually aligned goals of decreasing mucosal inflammation, improving mucociliary clearance, controlling infection, removing inflamed bone, and improving the delivery of medication to the target organ are approached through a variety of medical and surgical interventions. The earliest endeavors of rhinologists were directed toward infectious conditions of the nose and sinuses. Within the paranasal sinuses, modern endoscopes ushered in a renaissance in the basic science and clinical practice of rhinology. The surgical goals envisioned for surgery of the nose and sinuses would require specialized instrumentation that is complementary to the endoscope. Mucolytics, topical decongestants, allergy testing, surfactants, and large volume irrigations, sometimes incorporating high-dose topical steroids, are helpful adjuncts to the aforementioned medical strategies.