This book, ''Phytochemicals of Pteridophytes: Occurrence, Structures, and Biological Activity'', explores the chemical constituents of pteridophytes (lycophytes and ferns), emphasizing their occurrence, structures, and biological functions. It covers a wide range of phytochemicals, including aromatic compounds (e.g., acylphloroglucinols, flavonoids, lignans, selaginellins) and isoprenoids (e.g., monoterpenoids, norisoprenoids, sesquiterpenoids, diterpenoids, and steroids). The book examines the distribution of these compounds across various pteridophyte genera and species, highlights their structural diversity, and outlines their pharmacological properties. It also compares the phytochemical profiles of pteridophytes with those of algae and bryophytes.