Data in this chapter may be updated by searches of the Cochrane Library, Medline, PubMed and Ovid databases using the keywords: tonsils, tonsillitis, pharyngitis, sore throat, children, paediatric and carrying out further subsearches for anatomy, microbiology, immunology, complications and therapy. These were complemented by hand searches of current English language texts and the following journals: Journal of Laryngology and Otology, Clinical Otolaryngology, Laryngoscope, Archives of Otolaryngology, Annals of Otolaryngology, International Journal of Pediatric Otolaryngology. The information available from the published results of the National Prospective Tonsillectomy Audit available on the Royal College of Surgeons of England website (www.rcseng.ac.uk) has also been taken into account. In addition, the UK Department of Health (www.dh.gov.uk) and the National Institute for Health and Care Excellence (NICE) (www.nice.org.uk) websites were consulted.