In enzymology, a 15-oxoprostaglandin 13-oxidase (EC 1.3.1.48) is an enzyme that catalyzes the chemical reaction

(5Z)-(15S)-11alpha-hydroxy-9,15-dioxoprostanoate + NAD(P)+ ${\displaystyle \rightleftharpoons }$ (5Z)-(15S)-11alpha-hydroxy-9,15-dioxoprosta-13-enoate + NAD(P)H + H⁺

The 3 substrates of this enzyme are (5Z)-(15S)-11alpha-hydroxy-9,15-dioxoprostanoate, NAD⁺, and NADP⁺, whereas its 4 products are (5Z)-(15S)-11alpha-hydroxy-9,15-dioxoprosta-13-enoate, NADH, NADPH, and H⁺.

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 (5Z)-(15S)-11alpha-hydroxy-9,15-dioxoprostanoate:NAD(P)+ Delta13-oxidoreductase. Other names in common use include 15-oxo-Delta13-prostaglandin reductase, Delta13-15-ketoprostaglandin reductase, 15-ketoprostaglandin Delta13-reductase, prostaglandin Delta13-reductase, prostaglandin 13-reductase, and 15-ketoprostaglandin Delta13-reductase.

As of late 2007, 4 structures have been solved for this class of enzymes, with PDB accession codes 1V3T, 1V3U, 1V3V, and 2DM6.