This chapter discusses powered instrumentation in endoscopic sinus surgery, where variety of cutting blades and drill burs are available for this system, with varying angles and diameters to meet most rhinologic applications. The basic components of contemporary microdebrider systems include a power source, a handpiece, interchangeable blades, an irrigation system, and a suction source. The basic design of microdebrider blades incorporates a static, blunt outer sheath with a lateral fenestration and a mobile inner blade which possesses cutting edges which oppose the fenestration. The first irrigation systems introduced were simple gravity-fed lines introduced through a separate irrigation port on the blade sheath. Polypoid tissue in areas poorly accessible to standard instrumentation such as the floor of the maxillary sinus may be accessed with curved blades currently available. Another rhinologic application of powered instrumentation is submucous resection of inferior turbinates.