This is a clinical text for practising Allergists and Clinical Immunologists providing an evidence-based systematic problem oriented approach in investigation and management of this life threatening condition. This book has received excellent contributions from international experts from various countries and each chapter has embraced recent advances as well as international recommendations giving the reader 'best practice' parameters. Special features of this book include 'clinical cases' to compliment the text and put the reader into a clinical perspective and 'clinical pearls' at the end of each chapter with 'key take home messages'. We hope that this text will be helpful to the specialist physician in the provision of good quality of care for their patients.