A history of molluscan research in the western South China Sea (Singa-pore, Peninsular Malaysia, ailand,Cambodia,Vietnam and China) is described withmain references provided. e South China Sea has the most diverse bivalve faunain the world from 1200–1500 species. Regional species richness of bivalve mollusks in the western sea area varies from 344, at Singapore in the south, to 822, southern mainland China in the north, more of an indication of sampling eﬀorts and the stateof knowledge of the fauna than real biodiversity gradients. Other biodiversity-rich areas include the Gulf of ailand (594 species), Vietnam (815), Tonkin Gulf (368)and Hong Kong (299). e western part of the South China Sea is divided betweentwo provinces: the truly tropical Indo-Polynesian Province, and the subtropical Sino-Japanese Province; the boundary point lies around Hong Kong. Biogeographical problems as related to Vietnamese bivalve fauna are highlighted, and the biogeo-graphical zonation of the South China Sea based on concepts of western, Chinese, and Russian researchers is discussed. Problems in studying the region’s bivalve bio-diversity include inﬂated synonymy, a lack of trained, regionally-based taxonomists,good voucher collections, and a lack of funding for taxonomy. reats to molluscanbiodiversity are also discussed. Photographs of 117 species of bivalves belonging to 28 families are provided.