Marine sediments (0-5 cm) were sampled at 42 stations from Yeongil and Ulsan Bays of Korea in November 2000. Samples were analyzed for eight chlorobenzene congeners using multi-layer silica gel column chromatography and gas chromatography coupled to mass spectrometer detector (GC/MSD). The levels of total chlorobenzenes in marine sediments from Yeongil and Ulsan Bays were 2.92±1.65 ng/g dry weight and 11.16±12.25 ng/g dry weight, respectively. The highest concentrations exhibited in the stations from inner basin adjacent to terrestial sources. This result indicates that the hazardous contaminants such as chlorobenzenes derived from anthropogenic activities. Chlorobenzene contaminations in Yeongil and Ulsan Bays of Korea were relatively moderate in comparison to other marine environment in the world. The dominant congener among chlorobenzene species was 1,2,4-trichlorobenzene in marine sediments from Yeongil and Ulsan Bays, whereas tetrachlorobenzenes and pentachlorobenzene occupied a low proportion. There was a high correlation among the chlorobenzene species in Ulsan Bay, while there was partially significant correlation in Yeongil Bay.