Nitrate removal, nitrate removal velocity and denitrification rate were 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 nitrate removal rate was 19.454 mg N m^-2 d^-1 for site 1, 48.414 mg N m^-2 d^-1 for site 2, 46.982 mg N m^-2 d^-1 for site 3, and 48.896 mg N m^-2 d^-1 for site 4. The nitrate removal rate was in the order of site 4 > site 2 > site 3 > site 1 for the soil water columns. The removal velocity constants (k) of NO₃-N in site 1, 2, 3 and 4 were 0.4412, 1.3325, 1.4383 and 1.4270 per day, respectively. The removal velocity of nitrate in tested cores was rapid on the order of site 3 ≥ site 4 ≥ site 2 >> site 1. The maximum 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. The relative contribution of denitrification in site 1, 2, 3 and 4 were 6.35%, 3.98%, 4.77%, and 5.68% of total nitrate removal rate, respectively.