The Lepidoptera species recorded in Iceland, Norway, Sweden, Denmark, Finland, Estonia, Latvia and Lithuania are listed. The history of lepidopterology in the Nordic-Baltic area and in each country is outlined. The current understanding of Lepidoptera phylogeny is discussed, and the higher categories shown as a table. Phyllonorycter heringiella (Grønlien, 1932) is synonymized with P. salictella (Zeller, 1846) syn. rev., and P. brevilineatella (Benander, 1944) is synonymized with P. salicicolella (Sircom, 1848) syn. n. Syncopacma Meyrick, 1925 is synonymized with Aproaerema Durrant, 1897 syn. n., and this results in the following new combinations and recombinations: Aproaerema sangiella (Stainton, 1863) comb. n., A. cinctella (Clerck, 1759) comb. n., A. larseniella (Gozmány, 1957) comb. n., A. wormiella (Wolff, 1958) comb. n., A. ochrofasciella (Toll, 1936) comb. n., A. taeniolella (Zeller, 1839) comb. n., A. albifrontella (Heinemann, 1870) comb. n., A. vinella (Bankes, 1898) comb. rev., A. suecicella (Wolff, 1958) comb. n., A. polychromella (Rebel, 1902) comb. n., A. karvoneni (Hackman, 1950) comb. rev.. Caryocolum arenariella (Benander, 1937) is raised from rank as subspecies of C. schleichi (Christoph, 1872) to full species rank, stat. rev. Entephria byssata (Aurivillius, 1891) stat. rev. is reinstated as a valid species, distinct from the Nearctic E. punctipes (Curtis, 1835). Cosmia contusa (Freyer, 1849) comb. n. is transferred from Ipimorpha Hübner, 1821 to Cosmia Ochsenheimer, 1816. A total of 3 259 species have been recorded in the eight countries. The number of species for each country is: Iceland: 96, Norway: 2 286, Sweden: 2 804, Denmark: 2 583, Finland: 2 588, Estonia: 2 454, Latvia: 2 556, and Lithuania: 2 423.