In enzymology, a histidine transaminase (EC 2.6.1.38) is an enzyme that catalyzes the chemical reaction

L-histidine + 2-oxoglutarate ${\displaystyle \rightleftharpoons }$ (imidazol-5-yl)pyruvate + L-glutamate

Thus, the two substrates of this enzyme are L-histidine and 2-oxoglutarate, whereas its two products are (imidazol-5-yl)pyruvate and L-glutamate.

This enzyme belongs to the family of transferases, specifically the transaminases, which transfer nitrogenous groups. The systematic name of this enzyme class is L-histidine:2-oxoglutarate aminotransferase. Other names in common use include histidine aminotransferase, and histidine-2-oxoglutarate aminotransferase. This enzyme participates in histidine metabolism.