To find out the requirement of nitrogen, schedule of nitrogen application and feasibility of detopping for Bt-cotton and to assess their effects on growth, yield and fibre quality parameters, field experiment was conducted at Agriculture Research Station, Dharwad for two years (2005-06 and 2006-07) under irrigated conditions. Results indicated that increasing level of nitrogen from 80 to 120 and further to 160 kg/ha significantly increased seed cotton yield by 12 and 19 per cent, respectively. Application of N with recommended method of three splits (2267 kg/ha) was similar to application seven times (2237kg/ha). Detopping of Bt- cotton at 80 DAS did not improve the seed cotton yield significantly, but it reduced the plant height when compared with normal crop of cotton. In general, Bt-cotton with 120 kg N / ha applied in 4 splits and detopping (DtN2S2) produced fibers with greater fibre length, uniformity percentage, maturity ratio and fibre strength parameters as compared to other interactions. Hence the present recommendation of N can be enhanced to 120 kg/ha with present recommended schedule of application to increase yield and fibre quality under Dharwad conditions.