In enzymology, a N-methylalanine dehydrogenase (EC 1.4.1.17) is an enzyme that catalyzes the chemical reaction

N-methyl-L-alanine + H₂O + NADP⁺ ${\displaystyle \rightleftharpoons }$ pyruvate + methylamine + NADPH + H⁺

The 3 substrates of this enzyme are N-methyl-L-alanine, H₂O, and NADP⁺, whereas its 4 products are pyruvate, methylamine, NADPH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is N-methyl-L-alanine:NADP+ oxidoreductase (demethylating, deaminating).