It is a big challenge towards the scientists to meet the demand of ever increasing population in the world. Development of drug resistant pathogenic microorganisms, emergence of new diseases, appearance of life threatening viruses, management of post operative complication in patient with organ transplantation are some of the problems of twenty first century. It is necessary to identify safe and bioactive molecules to solve these problems. Different natural sources should be explored for this purpose. Endophytic fungus is one of the unexplored groups of organism. They are highly potent to produce bioactive compounds and can be considered as a source of novel secondary metabolites for medical, agricultural or industrial exploitation. This book comprises the research work on endophytic fungi. It provides the information about the endophytic fungi, procedure of isolation, identification and characterization of metabolites. This book will be useful to the young scientists especially those are working on drug development and drug discovery from natural product.