In enzymology, a phthalyl amidase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are phthalylamide and H<sub>2</sub>O, whereas its two products are phthalic acid and substituted amine.
This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amides. The systematic name of this enzyme class is phthalyl-amide amidohydrolase.