Nutsedge (Cyperus spp.) is one of the most troublesome and common weeds infesting cotton throughout the Southeast. With the rapid adoption of Roundup Ready cotton, nutsedge can be controlled effectively early season by applying Roundup; however, multiple applications of Roundup are often needed. Although two applications of Roundup may be applied overtop of Roundup Ready cotton prior to the fifth leaf, growers are often limited to a single over-the-top application of Roundup because of operation size and labor and time constraints. With only a single application of Roundup, nutsedge is usually only suppressed. Growers also have the option of using MSMA (Bueno 6) overtop of cotton for nutsedge control in several southeastern states. Due to the potential for cotton injury, MSMA at rates registered for over-the-top application to cotton only suppress nutsedge. Since neither a single application of Roundup nor MSMA applied overtop of Roundup Ready cotton adequately controls nutsedge, tank mixtures of Roundup and MSMA may be more effective than each herbicide applied alone. Therefore, field and greenhouse studies were conducted in Georgia and North Carolina to compare nutsedge control by Roundup/MSMA mixtures to Roundup and MSMA applied alone.