Abstract <p>A comparative analysis of the brittle star fauna of the seas surrounding the Russian Federation (White, Barents, Kara, Laptev, East Siberian, Chukchi, Bering, and Black seas and the Sea of Okhotsk and the Sea of Japan) was carried out based on both published and original data. The number of brittle star species in the seas under consideration totals 99. The largest number of species is found in the Sea of Okhotsk (54&#xa0;species), compared to the lowest number in the Black and White seas (four and five species, respectively). Three groups are naturally distinguished in the ophiuroid faunas of the study area: the fauna of the seas of the Arctic Ocean, the Far Eastern seas, and the Black Sea. In the group of fauna in the Arctic Ocean, the greatest similarity in species composition was noted between the Kara and Laptev seas; in the group of faunas in Far Eastern seas, it is between the Sea of Japan and the Sea of Okhotsk. The Bering and Chukchi seas showed the greatest similarity between these two groups. Autochthonous tendencies of fauna formation at the species level prevail in the Far Eastern seas of Russia, while allochthonous trends, to varying degrees, are observed in the other seas (introductions of species from neighboring seas with richer fauna).</p>