Canal wall down tympanomastoidectomy remains an important procedure for the management of advanced cholesteatomas and recalcitrant suppurative chronic otitis media. This course will discuss the indications for CWD surgery as well as delve into technical aspects of the procedure. Techniques to create a “good cavity” will be demonstrated with case presentations and surgical videos. Mechanisms to minimize the extent of the cavity including mastoid obliteration techniques will be discussed as well. Despite these best efforts, some patients have problems with chronic drainage from their cavities. Identification of what makes a “difficult” cavity will be addressed. A treatment algorithm for the “difficult cavity” will be defined and both medical and surgical options will be discussed. Audience participation and case based discussion will be utilized in this interactive session.