In enzymology, 3-methylbutanal reductase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are isoamyl alcohol (3-methylbutan-1-ol) and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are isovaleraldehyde (3-methylbutanal), reduced NADH, and a proton. The enzyme can also 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 3-methylbutanol:NAD(P)<sup>+</sup> oxidoreductase.