Present study has made a deep investigation covering, both important aspects, such as economics of production and marketing, besides, constraints in the cotton production in Haveri District. It also analyses the marketing cost and marketing margin, which exercise a dominant influence on its economics. Under such situation, it is a matter of paramount importance to study the seasonal variation in Bt cotton and non Bt cotton arrivals and their effect on prices of cotton, profitability of Bt cotton and non Bt cotton cultivation and the behaviour of farmers towards Bt cotton and non Bt cotton prices and their effect on area allocation, production and productivity of Bt cotton and non Bt cotton. In view of the above situations, there arises a need to interpret the phenomenon of cost and profitability of Bt cotton and non-Bt cotton. The findings of the study will be of interest and useful to local agencies, research scientists, policy makers and commercial organisations. The aim of the study is to analyse the problems associated with cost and profitability of production and marketing of Bt cotton and non-Bt cotton in Haveri District of Karnataka State India.