Zooplankton community in the major ports of Korea, which were characterized by a specific marine environmental condition during summer, was studied. Water temperature in the ports of western areas was higher and while those in the East Sea was lower. Contradictorily, the salinity was lowest in the western areas, while being highest in the eastern area. The Chl-a concentration was highest in the southern areas and lowest in the eastern one. Zooplankton taxa were most diverse in the western areas and simplest in the eastern one. Copepods predominantly occurred in the western areas, but their abundance relatively decreased in the southern and eastern areas. Cluster analysis revealed that copepod communities were classified into 3 summit groups, the western, southern and eastern areas. The results indicate that zooplankton communities in Korean ports may be affected by biological factors like Chl-a concentration in addition to environmental factor such as temperature and salinity.