This is a book which gives a brief introduction of phytochemistry, rhizome essential oil distillation, compound identification by GC-MS and antimicrobial activity by disc diffusion method of Zingiber cernuum and Costus speciosus. From the compound identification of Costus speciosus Zerumbone which was present in high percentage shows potential anticancer property. From the antimicrobial property studies both plant rhizomes show good activity.