The authors found five species of freshwater calanoids (Copepoda, Calanoida), in Taiwan, i.e., Sinocalanus laevidactylus, Pseudodiaptomus annandalei, Mongolodiaptomus birulai, Neutrodiaptomus tumidus, and Neodiaptomus schmackeri. S. laevidactylus and P. annandalei live in freshwater ponds near coastal areas. M. birulai, N. tumidus, and N. schmackeri primarily inhabit pools, ponds, reservoirs, and lakes. S. laevidactylus, P. annandalei, and N. schmackeri constitute new records of freshwater elements for the Taiwanese fauna. Allodiaptomus ueno, reported as Diaptomus ueno by Kikuchi (1936a) and Tropodiaptomus oryzanus reported by Kiefer (1937) were not found in our extensive collecting programme, and are believed to be now extinct in Taiwan.