Snake venoms are cocktails of enzymes and non-enzymatic proteins used for both the immobilization and digestion of prey. The most common snake venom enzymes include acetylcholinesterases, l-amino acid oxidases, serine proteinases, metalloproteinases and phospholipases A 2. Higher catalytic efficiency, thermal stability and resistance to proteolysis make these enzymes attractive models for biochemists, enzymologists and structural biologists. Here, we review the structures of these enzymes and describe their structure-based mechanisms of catalysis and inhibition. Some of the enzymes exist as protein complexes in the venom. Thus we also discuss the functional role of non-enzymatic subunits and the pharmacological effects of such protein complexes. The structures of inhibitor-enzyme complexes provide ideal platforms for the design of potent inhibitors which are useful in the development of prototypes and lead compounds with potential therapeutic applications. Snake venoms are cocktails of enzymes and non-enzymatic proteins. Here, we describe the structures of the common snake venom enzymes, namely, acetylcholinesterase, L-amino acid oxidase, phospholipase A2, serine proteinase, and metalloproteinase, and their complexes. We discuss the contribution of these structures in understanding the mechanisms of catalysis and inhibition as well as in the structure-based design of new, potent inhibitors © 2011 The Authors Journal compilation © 2011 FEBS.