The experiment was conducted with fourteen parental lines/varieties and their 37 F1 hybrids at Cotton Research Center Rangpur in the growing season 2011-12. 6x6 half diallel crosses were made in two hybridization plot and seven patents were unidirection crossed in another plot in the previous year. From above three crosses we obtained 37 Fi hybrids. The fourteen parental lines/varieties were as follows, 1. CB-1 (High yielder, earlier medium GOT%), 2. CB-3 (High yielder, early and medium GOT%, well adapted), 3. CB-5 (HYV, high GOT%, hairy leaf and disease resistant ), 4. CB-9 (High yielder, late maturation, well adapted, hairy leaf and low GOT%), 5. CB-I0 (High yielder, early and medium GOT%), 6. BC-088 (BAC-116, DC-120 glabrous, medium early, moderatly resistant & moderate high yielder, 7. BC-042 (BAC-55- Tx MaCAOS) red leaf and early but lowyielder, 8. China(inbreed line)-2 (high yielder, boll warm resistant, early maturation and high GOT%), 9. China (inbreed line)-3 (high yielder, boll warm resistant, early maturation and high GOT%), 10. China (inbreed line)-4 (high yielder, boll warm resistant, early maturation and high GOT%), 11. China (inbreed line)-5(high yielder, boll warm resistant, early maturation and high GOT%), 12 JA/09/F(inbreed line)- high yielder, boll warm resistant, early maturation and high GOT%, 13. JA/08/E (high yielder, boll warm resistant, early maturation and high GOT%, but suceptable to succking pest) and 14.B-4/10 (high yielder, boll warm resistant, early maturation and high GOT%). The F1 hybrids along with its parental lines were grown on 25 July 2011 in RCBD design with three replications. During crop growing periods standard cultural practices were followed. Data were collected on number of vegetative branches, number of main stem node of first fruiting branch (N.F.B), number of primary fruiting branches/plant, number of secondary fruiting branches, days to first flowering, days to first boll split, plant height, number of plants at harvested area, number of boll per plant, single boll weight, seed cotton yield per plot. Analysis of varience for different yield contributing traits were estimated by MAST AT Program. The percentage of heterosis and heterobeltosis were calculated according to the following formula-MP heterosis= {(F1- MP)-:- MP}xl00.Where MP=mean of the associated parents. BP= {(Fl - BP) -i- BP} xlOO Where BP=values of the better parents.