In enzymology, a N-methyl nucleosidase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are 7-methylxanthosine and H<sub>2</sub>O, whereas its two products are 7-methylxanthine and D-ribose.
This enzyme belongs to the family of hydrolases, specifically those glycosylases that hydrolyse N-glycosyl compounds. The systematic name of this enzyme class is 7-methylxanthosine ribohydrolase. Other names in common use include 7-methylxanthosine nucleosidase, N-MeNase, N-methyl nucleoside hydrolase, and methylpurine nucleosidase.