We studied the rotifer fauna of one of the most pristine peat-swamps in the Southern Thai province of Narathiwas, To Daengpeat swamp. The samples yielded a total of sixty-seven rotifer species. Of these, three -Keratella mixta (Oparina-Charitonova),Lecane enowi Segers & Mertens and Monommata dentata Wulfert- are new to the Oriental region and the Thai fauna, one,Keratella taksinensis n. sp., is new to science. The fauna consists mainly of cosmopolitan (sensu lato) species, complementedby some Paleotropical and endemic taxa, and is dominated by littoral-benthonic taxa, especially Lecane and, to a lesser extent,Lepadella.
