In enzymology, a -galactose 1-dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are D-galactose and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are D-galactono-1,4-lactone, reduced NADH, and a proton.
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 -galactose:NAD<sup>+</sup> 1-oxidoreductase. Other names in common use include -galactose dehydrogenase, beta-galactose dehydrogenase, and NAD<sup>+</sup>-dependent -galactose dehydrogenase. This enzyme participates in galactose metabolism.