On the basis of factor analysis, stations were grouped according to their similar characteristics of seawater quality. The data for factor analysis were collected from the 15 stations from Dukryang Bay to Ulsan Bay on the southern cost of Korea. The study was based on the data from 1991 to 2000. The 8 water quality items analyzed were temperature, salinity, pH, DO, COD, DIN (dissolved inorganic nitrogen), DIP (dissolved inorganic phosphorus), and SS (suspended solid). Analysis of 6 water quality items including DO with the exception of temperature and salinity showed that 15 stations were grouped into two zones, i.e., the western and the eastern coast, by the axis of Samcheonpo-Jinju Bay-south of Geoje, 3 seawater zones in all. The adjacent stations to the southward or northward but not those to the eastward or westward were classified into the same group. On the analysis of all of the 8 water quality items, the stations of Dukryang Bay and Goheung; and those of Onsan and Ulsan Bay were classified into the same group. Yeosu and Namhae stations were sectioned into 1 group on the all seawater quality items but DIP, Samcheonpo and south of Geoje stations another group on all seawater quality items but water temperature, and Masan and Busan stations in the other group on all seawater quality items but DO. The stations from Dukryang Bay through Goheung to east of Geoje were grouped together on the COD item, and this showed somewhat different tendency in other seawater quality items.