In enzymology, a (S)-2-hydroxy-fatty-acid dehydrogenase (EC 1.1.1.99) is an enzyme that catalyzes the chemical reaction

(S)-2-hydroxystearate + NAD⁺ ${\displaystyle \rightleftharpoons }$ 2-oxostearate + NADH + H⁺

Thus, the two substrates of this enzyme are (S)-2-hydroxystearate and NAD⁺, whereas its 3 products are 2-oxostearate, NADH, and H⁺.

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 (S)-2-hydroxystearate:NAD⁺ oxidoreductase. Other names in common use include dehydrogenase, L-2-hydroxy fatty acid, L-2-hydroxy fatty acid dehydrogenase, and 2-hydroxy fatty acid oxidase.