Butyrylcholine Esterase (BCHE) is a secreted protein that belongs to the type-B carboxylesterase/lipase family. BCHE is a major acetylcholine hydrolyzing enzyme in the circulation. It is detected in blood plasma and present in most cells except erythrocytes. BCHE is an esterase with broad substrate specificity. BCHE can contribute to the inactivation of the neurotransmitter acetylcholine. BCHE can degrade a large number of neurotoxic organophosphate esters. Thus, it plays important pharmacological and toxicological roles and is thought to be involved in the pathological progression. Defects in BCHE are the cause of butyrylcholinesterase deficiency (BChE deficiency) which is a metabolic disorder characterized by prolonged apnoea after the use of certain anesthetic drugs, including the muscle relaxants succinylcholine and other ester local anesthetics.