The Moscovian stratoype is located at the Moscow Basin (western Russian Platform), where fusulines have traditionally been used to subdivide the stage and to trace its lower boundary. However, fusuline assemblages from the lower Moscovian and the underlying upper Bashkirian show differences in species composition throughout Eurasia and also worldwide that make it difficult to establish correlations with the Russian Platform. This paper describes the succession of fusuline faunas yielded by three Cantabrian Zone (NW Spain) sections exposing the Bashkirian/Moscovian transition. Los Tornos and La Camocha sections are particularly relevant for they contain a fusuline record that could fill, at least partially, a gap existing at the base of the Moscovian stage stratotype. Another section, the Santo Firme section, is of interest in that it contains a cinerite that provided a numerical age at a level within the Bashkirian/Moscovian transition. Forty-nine fusuline taxa belonging to the Profusulinella Zone are described from these three sections, including the new species Schubertella multiforme, Profusulinella martinezi, Aljutovella asturiensis, and Eowedekindellina solovievae. In spite of the differences mentioned, attempts are made to correlate the fusulines from the Cantabrian Zone with the fusuline biozones defined in relevant Carboniferous areas of Eastern Europe (Russian Platform, Urals, Donets Basin).