On-farm split field comparisons were conducted in 1998 and 1999 to compare the economics of growing Bollgard with Roundup Ready (BG/RR) cotton to conventional cotton. Three split field comparisons were conducted each year with the BG/RR variety planted on one side of the field and the conventional variety planted on the other. Each variety/technology was managed independent of the adjacent variety/technology. Averaged across all fields and years, BG/RR cotton seed cost $1.45 per acre more than conventional cotton seed. Insecticides, Pix and Technology Fee costs including application indicated a savings of $26.50 for growing BG/RR cotton. Herbicides and Technology Fee costs were variable and ranged from $2.13 to $13.25 savings with conventional cotton depending on year. Herbicide application and cultivation averaged across all fields and years indicated a $9.08 savings for BG/RR cotton. Overall cost analyisis indicates a savings ranging from $20.88 to $32.00 for growing BG/RR cotton. Cotton lint yields were variable. BG/RR cotton demonstrated yields as good as or better than conventional varieties.