The European millipede genus Micropachyiulus Verhoeff, 1899 is revised based on type and non-type material, and on the available literature. The genus Hylopachyiulus Attems, 1904 is established as a junior subjective synonym of Micropachyiulus, syn. nov. Micropachyiulus ocellatus (Antić & Akkari, 2018) is thus listed as a new combination, comb. nov. Two new species-Micropachyiulus caucasicus sp. nov. and M. filiformis sp. nov.-are described from Russia and Romania, respectively. In addition, a presumably closely related monospecific genus, Armeniopachyiulus gen. nov., and its sole species A. pokr gen. et sp. nov. are described from Armenia. A brief discussion on the systematics and distribution of the studied taxa is presented.