We present the tight binding calculations of the lead selenide nanowires: energy spectra of quantum confined states as a function of nanowire radius, dispersion in the full Brillouin zone, and the radial part of local electronic state density, which helps us to recognise valley splitting in the spectra. Also, we compare our results to KP perturbation theory predictions.We show that the value of the valley splitting is comparable with the distance between two levels of size quantization and that it strongly depends on the arrangement of the atoms in the wire.