gamma-Lactamase belongs to the amidase. The (+) gamma-lactamses can be applied in the kinetic resolution of racemic gamma-lactam, which can produce (-) gamma-lactam efficiently. The (-) gamma-lactam enantiomer is an important synthon for the synthesis of carbocyclic nucleosides. Up to now seven strains of microbes were reported that produced gamma-lactamses. The crystal structure of (-) lactamase from Aureoacterium sp. was resoluted, and the catalytic mechanism based on the structure data analysis was alike with the alpha/beta hydrolase family. However, no structure data and mechanism theory is available for (+) lactamase till now. The future works focus on protein engineering of the gamma-lactamase to improve the catalysis of the protein, elucidation of the catalytic mechanism of the gamma-lactamase and the functions of the gamma-lactamase in vivo.