Decarboxylation reactions using microbial cells or enzymes are increasingly being used for the synthesis of enantiomerically pure compounds because of their high degree of regio- and stereo-specificity. Pyruvate decarboxylase, benzoylformate decarboxylase and phenylpyruvate decarboxylase enzymes are capable of acyloin-type condensation reactions leading to formation of chiral alpha-hydroxy ketones, which are versatile building blocks in the pharmaceutical and chemical industries. Availability of three-dimensional structures of some decarboxylases in recent years has facilitated understanding of reaction mechanisms and the creation of mutants with enhanced activity and stability.