In enzymology, 3alpha-hydroxy-5beta-androstane-17-one 3alpha-dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are etiocholanolone and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are etiocholanedione, 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 3alpha-hydroxy-5beta-steroid:NAD<sup>+</sup> 3-oxidoreductase. Other names in common use include etiocholanolone 3alpha-dehydrogenase, etiocholanolone 3alpha-dehydrogenase, and 3alpha-hydroxy-5beta-steroid dehydrogenase. This enzyme participates in androgen and estrogen metabolism.