The diagnosis and treatment of the diseases of the nose, paranasal sinuses and skull base have changed dramatically in the past few years, transforming rhinol ogy in one of most exciting and attractive medical fields. The increasing advance in this area has addressed the ENT physicians to keep up with the expanding information in the high tech area of sinus surgery and its expansion into skull base surgery. The intention of this book is to present in a unique way basic information on Anatomy, Endoscopy, Rhinomanometry, Imaging, Allergy, Nasosinus Infection, and Polyposis followed by by clinical and surgical chapters written by some of the most experienced rhinosurgeons around the world. We belive that this book will be of value for all levels of Otolaryngology, from house officers to experienced surgeons and, although principally for Otolaryngologists, Radiologists, Patholo gists, Maxillofacial surgeons, Ophthalmologists, Neurosurgeons, and Infectious Diseases Specialists may find the book of value because of its overlap with their interests. We would like to show that, both from the technical and conceptual points of view, success can be achieved using different techniques and philosophies. Cer tainly, both endoscopic instrumentation and the surgical microscope have proved to be of great assistance in nasal and sinus surgery, and now image systems are providing further progress.