2-(3-Methyl-2-oxoquinoxalin-1-yl)- N -(4-methyl-phen-yl)acetamide.

The quinoxaline moiety in the title mol-ecule, C 18 H 17 N 3 O 2 , is not quite planar and the p -tolyl group is rotationally disordered over two nearly equally populated sets of sites. In the crystal, N-H⋯O and C-H⋯O hydro-gen bonds form chains extending along the b -axis direction. Due to the disorder of the p -tolyl rings, short C⋯C distances are observed between adjacent chains.