In enzymology, Delta14-sterol reductase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are 14-demethyllanosterol and oxidised nicotinamide adenine dinucleotide phosphate (NADP<sup>+</sup>). Its products are 4,4-dimethyl-5ñ-cholesta-8,14,24-trien-3ò-ol, reduced NADPH, and a proton.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-CH group of donor with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is 4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol:NADP+ Delta14-oxidoreductase. This enzyme participates in biosynthesis of steroids.