Cotton crop has been cultivated predominantly in many parts of India, but its productivity is one of the lowest in the world mainly due to severe pests attack. Farmers are unable to control the bollworm attack, which is the key pest in cotton destroying up to 80 percent of crop output. Bt (Bacillus Thuringiensis) cotton introduced during March 2002 for commercial cultivation in India is considered to be an important variety in protecting the crop from bollworm attack. Many studies have been carried out since the introduction of Bt seed focusing on various aspects, but the controversies about the benefits of the new seed variety have been continuing. In this paper, an attempt has been made to study the productivity and profitability of Bt cotton by comparing with non-Bt cotton using farm level data collected from sample farmers in Tamil Nadu State. This study shows that while reducing the consumption of pesticides, Bt cotton helps to increase its productivity and profitability considerably as compared to non-Bt cotton.