This book is intended as a reference book for researchers in Biology field.The present book is the outcome of the results of identification of CTLA-4gene polymorphism in graves' hyperthyroidism are explained in detail by the author. The aim of the book is to provide a comprehensive introduction to the subject of Biology which is very helpful to researchers. In preparing text, the author has taken special care to present the topics in a coherent, simple and straight forward manner.This book is broadly classified into six contents namely INTRODUCTION, METHODOLOGY, RESULTS, DISCUSSION, REFERENCES and APPENDICES. We really enjoyed very much while preparing this book for the sub chapters also. My vision of this book is for it to get elaborated with more of materials technology and should be the complete guidance for 'CTLA-4 gene polymorphism'.We are thankful to God and our Parents. We also give great thanks to our college for their full support to publish this book.