The light emission characteristics of ultraviolet (UV) AlGaN/AlN quantum well (QW) structures with the AlGaN delta-layer in the active region were investigated using the multiband effective-mass theory and non-Markovian gain model. In a wavelength range of 220–280 nm, AlGaN/AlN QW structures with the ultrathin AlGaN layer are shown to have much larger light emission than conventional AlGaN/AlN QW structures. This can be explained by the fact that the internal field in the well is reduced and the optical matrix element is greatly enhanced with the inclusion of the low-bandgap AlGaN delta-layer. We expect that AlGaN/AlN QW structures with the ultrathin AlGaN layer can be used as a light source with a high efficiency in UV region.