The fauna of the Northwestern region of Russia comprises 285 species of bloodsucking insects. The number of species of mosquitoes and lice in the Northwest constitute 40% of the total numbers in the Russian fauna; that of the biting midges, 38%; horseflies, 35%; blackflies, 30%, and fleas, 19%. Representatives of 4 dipteran families of the “gnus” complex, and also lice and fleas of the Northwestern Russian fauna possess ranges of 12 types, most of which include large part of the Holarctic or Palaearctic; 57 species (20%) of the species have Holarctic ranges; 82 species, or 28%, trans-Palaearctic ranges; 49 species, or 17%, Western-Central Palaearctic ranges; and 73 species, or 25%, Western-Palaearctic ranges. The fraction of species (8) with other range types is 19%. A synopsis of the species groups characterized by these types of ranges is given. Species with ranges extending as far northwards as the tundra zone constitute 13%, those with ranges including the taiga zone, 60%, and those with other range types, 27% of the fauna.