Field trials were conducted in Alabama during 1996 and 1997 to evaluate Roundup Ready cotton in different tillage systems for weed control, seed cotton yield and economic value. Trials were conducted at the Tennessee Valley Substation (TVS) in north Alabama, the E.V. Smith Research farm (EVS) in central Alabama, and the Wiregrass Substation (WGS) in southeast Alabama. Soil types at EVS and WGS are sandy loams found in much of the Coastal Plain, while the soil at TVS is a clay loam. Systems consisted of: 1) conventional tillage using Prowl (2 pts/A) incorporated, Cotoran (3 pts/A) preemergence (pre), Staple (1.2 oz/A) banded post over-the-top (pot), and Caparol + MSMA (2 pts + 2 pts/A) layby; 2) notill with Prowl + Cotoran pre, Staple pot, and Caparol + MSMA layby; 3) notill with Roundup Ultra (2 pts/A) pot, post-directed (pds), and layby; 4) notill with Roundup Ultra pot and pds, and Bladex layby; 5) Stale seedbed with Treflan (1.5 pts/A) incorporated in March followed by Roundup Ultra pot and pds, and Bladex layby; 6) notill with Cotoran pre, Roundup Ultra pot and pds, and Bladex layby. The stale seedbed and all notill systems received a preplant foliar application of Roundup Ultra at 2 pts/A to kill emerged weeds prior to planting. Treatments were applied to plots 4 rows wide by 30 to 40 feet long, each replicated 6 times. Cotton varieties DPL 5415RR was used at TVS, and DPL 5690RR at EVS and WGS. Late season weed control was rated on a scale of 0 to 100 where 0 = no control and 100 = complete control. Seed cotton was harvested by plot with spindle pickers and converted to lint by assuming a 40 percent lint yield. Net returns were calculated for each plot using actual yields and Alabama Cooperative Extension System cotton production budgets.