This book firstly presents the advances in the understanding of epidemiology, genetics, mechanisms, phenotypes, and immunology of this disorder. In the following chapters, details in clinical diagnosis of CRS are summarized, especially clinical characteristics in paediatric CRS. Later chapters introduce medical, surgical, and innovative treatments of CRS, with brief case studies. The role of allergies, asthma, allergic fungal rhinosinusitis, and systemic diseases are also discussed. With the illustrative figures, this book is a comprehensive and quick reference to otolaryngologists, paediatricians, family care physicians, allergists, professional clinical staff, and medical students.