Abstract - Distribution characteristics of two dominant paracalanids of the family Paracalanidae on temperature and salinity were studied in the brackish and coastal waters from the West and South coasts of Korea. Bestiolina coreana mainly occurs in a range of 29.8~31.3 psu salinity and temperature of more than about 20?C, while Paracalanus parvus s. l. mainly occurs in a range 17~20?C temperature and more than 30 psu salinity. The fact clearly indicates that temperature and salinity was a major factors in spatio-temporal distribution between these two paracalanids.