The text has been written in simple and lucid language. A preview has been presented in the beginning of each chapter. Life cycles of parasites are depicted in quick recapitulation of whole life cycle. To make learning easier, well labelled diagrams and tables have been furnished at appropriate places. Important terms have been highlighted by using italic and bold letters. Latest development and new concepts have been included. Significant practical aspects have been listed in the form of appendices. The book is meant for undergraduate and postgraduate students and persons working in health related professions. It is hoped that the readers will find this book of immense help. Their suggestions and new ideas for further improvemnt of the book shall always be appreciated.