Denitrification rate was determined for various freshwater wetland types in the Mississippi River Coastal delta plain. Site 1 and 4 were collected from forested-tupelo dominated wetland, and site 2 and 3 were from floating emergent marsh. The maximum N2O emission was 7.47 mg N m-2 for site 1 at day 6 after the addition of nitrate, 6.96 mg N m-2 for site 2 at day 4, 6.63 mg N m-2 for site 3 at day 3, and 9.64 mg N m-2 for site 4 at day 4. The denitrification rate was determined using the acetylene inhibition method 1.24 mg N m-2 d-1 for site 1, 1.93 mg N m-2 d-1 for site 2, 2.24 mg N m-2 d-1 for site 3, and 2.78 mg N m-2 d-1 for site 4. The maximum denitrification rate was in the order of site 4 > site 3 > site 2 > site 1.