The use of sulfamethazine and tetracycline to maintain animal health in the swine, poultry or cattle feedlots operations results in significant application of these veterinary pharmaceuticals to the landscape during grazing or manure disposal operations. Drinking water sources contaminated by these veterinary antibiotics have raised public health concern in Southwestern Missouri and other regions of US. Recent studies have demonstrated the benefits of using multi-species vegetated buffers to reduce the transport of the veterinary antibiotics. However, the fates of these antibiotics in vegetative buffers and their impact on the rhizosphere microbial activities have not been well documented. A growth chamber study was conducted to investigate the rhizodegradation of 3H sulfamethazine and 3H tetracycline and the relationship of degradation with soil enzyme activities in the rhizosphere of four selected plant species. The plant species included: 1) switchgrass, 2) eastern gammagrass, 3) orchardgrass, 4) hybrid poplar. All plant treatments were grown in pots containing Mexico silt loam. Pots containing soil without plants were used as controls. Plants were grown to maturity (~3 months), and the rhizosphere soils were collected. Radio labeled sulfamethazine or tetracycline was then applied to the rhizosphere soil and incubated in the dark for 100 days. The developed knowledge will help us understanding the fate of the 2 antibiotic and their associated interaction with the soil microbial activities. Moreover, the grass species showing high rhzodegradtion potential could be incorporated into buffer designs to mitigate the impacts of these two antibiotics in the environment.