N-acetylglucosaminyldiphosphodolichol N-acetylglucosaminyltransferase (, UDP-GlcNAc:dolichyl-pyrophosphoryl-GlcNAc GlcNAc transferase, uridine diphosphoacetylglucosamine-dolichylacetylglucosamine pyrophosphate acetylglucosaminyltransferase, N,N'-diacetylchitobiosylpyrophosphoryldolichol synthase) is an enzyme with systematic name UDP-N-acetyl-D-glucosamine:N-acetyl-D-glucosaminyl-diphosphodolichol N-acetyl-D-glucosaminyltransferase. This enzyme catalyses the following chemical reaction