The field experiment was conducted at College of Agriculture Farm, Raichur on medium black soil during kharif, 2009 to study the weed management in Bt cotton (Gossypium hirsutum L.) under irrigation. The results revealed that among the weed management treatments, weed free check recorded significantly higher uptake of nutrients (111.01, 31.21 and 129.11 NPK kg ha-1and was followed by pendimethalin 38.7 CS (PRE) + quizalofop ethyl 5 EC (POE) + IC and HW at 60 DAS (T12). With regards to yield and economics, pendimethalin 38.7 CS (PRE) + quizalofop ethyl 5 EC (POE) + IC and HW at 60 DAS (T12) gave significantly higher seed cotton yield (14.06 q ha-1) and higher gross returns (`35,150 ha-1), net returns (`11,857 ha-1) and BC ratio (1.51)