Since 1987, the most recent issues on tonsils and mucosal immunity have been discussed regularly at the 'International Symposiums on Tonsils and Mucosal Barriers of the Upper Airways' (ISTMB). This book is a summary of the topics presented during the 7th ISTMB covering both basic and clinical research on tonsils and upper airways. Presented are issues such as immunology and mucosal defense systems, bacteriology and virology, mucosal vaccine for upper airway infections, MALT, NALT and LALT, clinical manifests and pathogenesis of tonsil-related diseases such as IgA nephropathy, palmoplantal pustulosis, reactive arthritis diseases, and more related disorders. Further contributions reflect the association of tonsils with otitis media, allergic diseases in the upper airways, obstructive sleep apnea syndrome, and medical and surgical treatments for tonsil diseases. Otolaryngologists, pediatricians and immunologists who seek to unravel the mystery of the tonsil will find this volume of great assistance on their way to accomplish this task.