We measured the fluxes of COD, TN and 55 in addition to composition and quality of sediment in Komso Bay, West Coast of Korea. The fluxes of TN, SS and COD were measured during flood tide and ebb tide in April and August, 2000. Denitrification rates in the sediments was also measured by direct produced N2 gas technique on April and August from 1999 to 2000 in the same sea area. The composition of the sediments were 0.33~5.67 % of sand, 20.2~25.6 of gravel and 68.7~77.0 % of silt. Ignition loss of the sediments were 6.58~7.50 %. The concentration of hydrogen sulfide in the sediments were 0.028~0.326 mg/gㆍdry and oxidation reduction potential of the sediments were -28~-15 mV Diurnal fluxes of COD, total nitrogen, and suspended solids with tidal current and denitrification rate in the tidal flat have been determined in Komso Bay The diurnal net flux of COD was same in April. While 14.4 ton COD/hr of net influx into the tidal flat was recorded in August. The diurnal net influx of total nitrogen was 0.16 ton N/hr in April and 1.13 ton N/hr in August. The diurnal net influx of suspended solids was 0.05 ton SS/hr in April, and also net influx of suspended solids was 0.29 ton SS/hr in August. The overall purification ability of the tidal flat were estimated 0.00~5.69 g COD/m²/day, 0.06~0.45 g N/m²/day and 0.02~0.12 g SS/m²/day for COD, TN and SS, respectively. Denitrification rate was 0.009~1.720 m mole N₂/m²/day (average 0.702 m mole N₂/m²/day) in April and 0.033~0.133 m mole N₂/m²/day (average 0.077 m mole N₂/m²/day) in August, 1999. 0.000~l.909 m mole N₂/m²/day (average 0.756 m mole N₂/m²/day) in April, 0.000~1.691 m mole N₂/m²/day (average 0.392 m mole N₂/m²/day) in August, 2000. Even with a wide range of denitrification rate depending on the sampling location and studied periods, the average denitrification rate was estimated 0.482 m mole N₂/m²/day in the tidal flat of Komso Bay.