In enzymology, carnitine 3-dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are carnitine and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are 3-dehydrocarnitine, 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 carnitine:NAD<sup>+</sup> 3-oxidoreductase.