In enzymology, cis-3,4-dihydrophenanthrene-3,4-diol dehydrogenase () is an enzyme that catalyzes the chemical reaction
The two substrates of this enzyme are (3S,4R)-3,4-dihydrophenanthrene-3,4-diol and oxidised nicotinamide adenine dinucleotide (NAD<sup>+</sup>). Its products are phenanthrene-3,4-diol, reduced NADH, 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 (+)-cis-3,4-dihydrophenanthrene-3,4-diol:NAD+ 3,4-oxidoreductase. This enzyme participates in naphthalene and anthracene degradation.