Prenylation of aromatic secondary metabolites is an important process involved in the biosynthesis of many biologically active compounds in plants and animals. Many prenylated natural products have been shown to exhibit very good anti-tumor, anti inflammatory and antimicrobial activities. The addition of prenyl side chain to an aromatic secondary metabolite often affects its pharmacological activity. The aim of this review is to examine the influence of the prenyl side chain on the pharmacological activities of some classes of aromatic secondary metabolites and the potential application of prenylation in the development of novel drugsKeywords: Secondary metabolite, Prenylation, Aromatic, Ras antagonist, Novel drugs