The chemical and physical structure of a TiAlN/VN multilayer, of average layer thickness 3.4 ± 0.4 nm, was characterized using a spherical aberration-corrected STEM, utilizing a nominal 0.1-nm beam, by HAADF and EELS. The interface between layers was shown to be rough, with local thickness variations evident in layer thickness. Chemical mixing between layers was identified, consistent with numerical modelling of the deposition flux and layer growth. The implications of the compositional modulation are discussed.