In enzymology, 3-(imidazol-5-yl)lactate dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are (S)-3-(imidazol-5-yl)lactic acid and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are imidazole-4-pyruvic acid, reduced NADH, and a proton. The enzyme can use the alternative cofactor, nicotinamide adenine dinucleotide phosphate.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD<sup>+</sup> or NADP<sup>+</sup> as acceptor. The systematic name of this enzyme class is (S)-3-(imidazol-5-yl)lactate:NAD(P)<sup>+</sup> oxidoreductase. This enzyme is also called imidazol-5-yl lactate dehydrogenase.