Herbal biomolecules are the agents that represent a diverse variety of organic compounds obtained mainly from plant sources and exhibit a variety of biological functions. The herbal biomolecules majorly constitute the primary and secondary plant metabolites. The current chapter focuses on the chemistry of such herbal biological molecules. The major biomolecules listed include carbohydrates, oils, resins, alkaloids, glycosides and tannins and their classified derivatives. © 2022 Elsevier Inc. All rights reserved.