Twenty-five species of proetid trilobites are distinguished in the Ordovician of Scandinavia. They are distributed among the established genera Proetus Steininger, 1831, Decoroproetus Pfibyl, 1946, Eremiproetus R. & E. Richter, 1919, and Cyphoproetus Kegel, 1927 and the new genera Ascetopeltis (type species A. bockeliei sp. nov.), Stenoblepharum (type species Paraproetus warburgae Pfibyl, 1964), and Xenocybe (type species X. micrommata sp. nov.). Nine new species are defined: Ascetopeltis bockeliei, A. lepta, Decoroproetus bodae, D. campanulatus, D. evexus, Stenoblepharum norvegicum, S.? striatum, Eremiproetus agellus and Xenocybe micrommata. The new genus Parvigena (type species Proetus parvigena Warburg, 1925), of unknown affinities, is placed in family uncertain. The greatest diversity of species is found in late Ordovician reef or reeflike deposits, and species from such horizons are comparable with those occurring in the Kildare Limestone, Ireland, and in the Whitehead Formatien, Quebec. Species found in non-reef deposits are mostly distinct from those of the reefs, but are the same as, or comparable with those found in similar strata in Britain and Poland.