Natural products called secondary metabolites (SMs) are heterogeneous low-molecular-mass molecules which function in basal physiological activities, growth, development, survival, and fitness of the producing organisms. The main fungal SMs can be classified in four classes, i.e., polyketides, nonribosomal peptides, terpenes, and alkaloids. These groups of SMs are synthesized by polyketide synthases (PKSs), nonribosmal peptide synthetases (NRPSs), terpene synthases/cyclases, and dimethylallyl tryptophan synthases, respectively. Recently a novel type of SM named ribosomally synthesized and posttranslationally modified peptides or ribosomal peptides (RiPs) has become known in bacteria and fungi, including Aspergillus. The ascomycetous fungus Aspergillus with over 330 species represents some of the most common fungi in the environment. Aspergillus species are among the most potent fungi capable of biosynthesizing a vast array of primary and SMs including PKs, NRPs, RiPs, terpenes, and alkaloids. This chapter discusses the recent advances in SM discovery in Aspergillus species
