A field experiment was conducted in 1999 at the Pee Dee Research and Education Center, Florence, SC, to compare yields of Roundup Ready cotton cultivars under two weed management systems (Roundup Ultra only system, standard management system) with yield of conventional cultivars under a standard herbicide system. The standard herbicide system consisted of Prowl @ 2.4 pt/ac preplant-incorporated, Cotoran @ 1.75 qt/ac preemergence, Staple @ 1.2 oz/ac + surfactant (0.25% v/v) applied postemergence (POST), and Cotton-Pro + MSMA @ 1.2 qt + 2.67 pt/ac applied POST-directed at layby. In the Roundup Ultra only system, Roundup Ultra @ 1 qt/ac was applied POST and was POST-directed at layby. POST treatments were applied to cotton in the four-leaf stage of growth.