In enzymology, a mevaldate reductase (NADPH) (EC 1.1.1.33) is an enzyme that catalyzes the chemical reaction

(R)-mevalonate + NADP⁺ ${\displaystyle \rightleftharpoons }$ mevaldate + NADPH + H⁺

Thus, the two substrates of this enzyme are (R)-mevalonate and NADP⁺, whereas its 3 products are mevaldate, NADPH, 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 (R)-mevalonate:NADP⁺ oxidoreductase. Other names in common use include mevaldate (reduced nicotinamide adenine dinucleotide phosphate), reductase, and mevaldate reductase (NADPH).