Constructed wetlands have been used to treat diary and swine wastewater. In wetlands microbial communities play a vital role in elemental transformations. The classical microorganisms that are responsible for these biochemical functions are well known. However, enough data is not available on different microbial communities that exist in wetlands. The variation in microbial communities could be spatial, nutrients availability, oxidation-reduction conditions, and other inhibitory substrates. A number of molecular biologcal methods have been used to analyze soil microbial communities under various ecological practices. In the present study PCR-dependent DGGE molecular biological method was used to compare the spatial differences in microbial communities in marsh-pond-marsh constructed wetlands treated with swine wastewater. Correlation of microbial communities with the nutrients concentration, oxidation-reduction, pH,BOD, and COD parameters will be presented.