An economic evaluation of Bt cotton technology was undertaken using data from two on-farm experiments in South Carolina. Spraying for tobacco budworm (Heliothis virescens) and cotton bollworm (Helicoverpa zea) were not required in Bt cotton as the thresholds were not exceeded, but methyl parathion was applied at least once to control for stinkbugs. In both sites, cost savings from reduced insecticide application were evident. Actual experimental yield for Bt cotton was higher than non-Bt cotton in the Barnwell county site, while Bt yield was lower than non-Bt yield in the Lee county site. These results made Bt cotton very profitable in Barnwell county but unprofitable in Lee County. Further statistical analysis revealed that there was no significant difference between the yields of Bt and non-Bt cotton in both sites. Economic analysis that assumes constant yield levels showed that Bt cotton was profitable in both sites. Using Bt cotton technology was also found to be more efficient than non-Bt cotton. However, Bt cotton was riskier than non-Bt cotton in both sites. Although it seems advisable to adopt Bt cotton over non-Bt cotton based on the exprimental results for one year, the risk factor plus several implicit factors must also be considered before a definitive decision on the Bt cotton technology is made.