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 $N_2O$ emission was $7.47mg;N;m^{-2}$ for site 1 at day 6 after the addition of nitrate, $6.96mg;N;m^{-2}$ for site 2 at day 4, $6.63mg;N;m^{-2}$ for site 3 at day 3, and $9.64mg;N;m^{-2}$ for site 4 at day 4. The denitrification rate was determined using the acetylene inhibition method $1.24mg;N;m^{-2}d^{-1}$ for site 1, $1.93mg;N;m^{-2}d^{-1}$ for site 2, $2.24mg;N;m^{-2}d^{-1}$ for site 3, and $2.78mg;N;m^{-2}d^{-1}$ for site 4. The maximum denitrification rate was in the order of site 4 > site 3 > site 2 > site 1.