This book is useful for pharmacy graduates, post graduates and research scholars who wish to pursue their research in the field of phytochemistry. Phytochemical screening and invitro antioxidant activity of chromalaena odorata was presented in a systematic manner. In this book, Chapter 1 deals with the introduction of phytochemical screening and antioxidant activity with plant profile. Chapter 2 deals with the literature survey of chromalaena odorata. Chapter 3 deals with the systematic phytochemical screening methods for chromalaena odorata. Chapter 4 deals with invitro antioxidant activity methods. Chapter 5 deals with summary and conclusion.