In enzymology, (S)-3-hydroxyacid-ester dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are ethyl (S)-3-hydroxyhexanoate and oxidised nicotinamide adenine dinucleotide phosphate (NADP). Its products are ethyl 3-oxohexanoate, reduced NADPH, and a proton.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD or NADP as acceptor. The systematic name of this enzyme class is ethyl-(S)-3-hydroxyhexanoate:NADP 3-oxidoreductase. This enzyme is also called 3-oxo ester (S)-reductase.