Forest and grass riparian buffers are a common conservation practice to control nonpoint source pollution. In the lower midwestern United States, there is significant interest in incorporating a once common native riparian species, giant cane (Arundinaria gigantea) in riparian restoration designs. Thus, assessing the water quality benefits of giant cane buffers is warranted. Ground water nitrate and ammonium concentrations were measured at the field edge (0 m), and 1.5, 3.0, 6.0, 9.0, and 12.0 m from the field edge through giant cane and forest riparian buffers adjacent to agricultural fields along three streams in southern Illinois. Ground water nitrate and ammonium were not different between the giant cane and forest riparian buffers, nor were there significant reductions in these nutrients through the riparian zones when all three sites were considered. However, site-specific regressions of nutrient concentration vs. distance showed significant reductions (>80%) in nitrate through two forest and one cane riparian buffers, and a significant reduction in ammonium (95%) through a cane buffer. Our results indicate that buffer effectiveness may be dependent on landscape position and water table depth.