The enzyme ñ-N-acetylglucosaminidase (, ñ-acetylglucosaminidase, N-acetyl-ñ-D-glucosaminidase, N-acetyl-ñ-glucosaminidase, ñ-D-2-acetamido-2-deoxyglucosidase) is a protein associated with Sanfilippo syndrome, with systematic name ñ-N-acetyl-<small>D</small>-glucosaminide N-acetylglucosaminohydrolase. It catalyses the hydrolysis of terminal non-reducing N-acetyl-<small>D</small>-glucosamine residues in N-acetyl-ñ-<small>D</small>-glucosaminides, and also UDP-N-acetylglucosamine.