In enzymology, an isochorismatase (EC 3.3.2.1) is an enzyme that catalyzes the chemical reaction

isochorismate + H₂O ${\displaystyle \rightleftharpoons }$ 2,3-dihydroxy-2,3-dihydrobenzoate + pyruvate

Thus, the two substrates of this enzyme are isochorismate and H₂O, whereas its two products are 2,3-dihydroxy-2,3-dihydrobenzoate and pyruvate.

This enzyme belongs to the family of hydrolases, specifically those acting on ether bonds (ether hydrolases). The systematic name of this enzyme class is isochorismate pyruvate-hydrolase. Other names in common use include 2,3-dihydro-2,3-dihydroxybenzoate synthase, 2,3-dihydroxy-2,3-dihydrobenzoate synthase, and 2,3-dihydroxy-2,3-dihydrobenzoic synthase. This enzyme participates in the biosynthesis of siderophore group (nonribosomal).

As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes 1NF8, 1NF9, and 2FQ1.