This study described the spatial distribution of dinoflagellate cyst assemblages in the Ulsan Coastal Waters (UCW). Surface sediment samples from 15 stations revealed the occurrence of 33 species involving the Groups Protoperidinioid (51.5%), Gonyaulacoid (30.4%), Calciodineloid (9.1%), Gymnodinioid (3.0%), Diplopsallid (3.0%) and Tuberculodinioid (3.0%). The recorded cyst abundance in the UCW recorded was low (260~1,680 cysts g-dry-1) compared to Korean coastal waters. The abundance of heterotrophic cysts is higher in the Ulsan harbour and northwestern parts of UCW with eutrophic areas, however autotrophic species are more prevalent in the southern parts with open sea environments. The dinoflagellate cyst assemblages in the UCW were characterized by the dominance of Gonyaulax scrippsae, Protoperidinium sp. (Brigantedinium sp.), and Gonyaulax spinifera complex. The advent of the toxic dinoflagellate, Pyrodinium bahamense var. bahamense was recorded for the first time in the East-south sea of Korea. Therefore, as a result of ongoing monitoring and management for new toxic dinoflegallates from tropical or subtropical regions, analysis of dinoflagellate cyst assemblages in the UCW has been deemed necessary.