A faunal study in the Bay of Nhatrang (southern Vietnam) in 2006-2009, using scuba diving at 0-30 m of depth, revealed 32 unstalked crinoid species of five families. An annotated list of crinoid species, the data on their frequency and distribution in the bay, and descriptions of color and ecological features of the majority of species are provided. Twelve species are new for Vietnam and five are new for the South China Sea. The majority of species (21) are diurnal and only five are nocturnal. Ten of diurnal species inhabit open surfaces, nine are cryptobionts, and two are specialized inhabitants of gorgonian corals. The diversity and taxonomic composition of crinoids of Vietnam and other water areas of the Indo-West Pacific are compared. Key words: Echinodermata, crinoids, biodiversity, Vietnam, South China Sea. DOI: 10.1134/S0031030112080084