The tip of the South American cone is one of the most interesting Subantarctic areas, both biogeographically and ecologically. Nonetheless, knowledge of the area's biodiversity, in particular that of the subtidal marine habitats, remains poor. Therefore, in 2004, a biodiversity research project was carried out as a part of the cruise Cimar-10 Fjords, organized and supported by the Chilean National Oceanographic Committee (CONA). The results of the subtidal marine mollusk surveys are presented herein. The samples were collected aboard the Agor 60 "Vidal Gormaz" in winter 2004. The study area covered the northern Chilean Patagonia from Seno de Relocanví (41°31'S) to Boca del Guafo (43°49'S), on the continental shelf from 22 to 353 m depth. The Mollusca were collected at 23 sampling sites using an Agassiz trawl. In total, 67 species were recorded: 4% Polyplacophora (Leptochitonidae, Ischnochitonidae), 58% Gastropoda (Lepetidae, Fissurellidae, Trochidae, Turbinidae, Calyptraeidae, Capulidae, Naticidae, Ranellidae, Cerithiopsidae, Epitoniidae, Muricidae, Buccinidae, Columbellidae, Nassariidae, Volutidae, Cancellariidae, Turridae, Pyramidellidae, Acteonidae, Chilinidae), 36% Bivalvia (Nuculidae, Yoldiidae, Malletiidae, Tindariidae, Limopsidae, Phylobryidae, Mytilidae, Pectinidae, Propeamussidae, Lucinidae, Thyasiridae, Neoleptonidae, Carditidae, Condylocardiidae, Veneridae, Tellinidae, Lyonsiidae, Pandoridae, Cuspidariidae), and 1% Scaphopoda (Rhabdidae). Our results show a high proportion of southern (Magellanic) subtidal species; 45 species (67%) are strictly Magellanic or Antarctic and another 16 (24%) were widespread species, with distributions extending to the south of our study area. Only six species (9%) were strictly Peruvian.