This study was conducted to determine some traits effective on fiber yield at F1 hybrids of some cotton cultivars belong to Gossypium hirsutum L. species and Aşkabat 100 cultivar belong to Gossypium barbadense L. species. According to the results 7 combinations showed positive heterosis for cotton yield, number of monopodial branches, number of sympodial branches and plant height and, also 6 combinations showed positive heterosis for fiber yield and boll number per plant while, 7 combinations showed negative heterosis for ginning turnout. Combinations when investigated for heterobelthosis; 6 combinations showed negative heterobelthosis for cotton yield, 7 combinations showed negative heterobelthosis for ginning turnout and giber yield, 3 combinations showed negative heterobelthosis for number of monopodial branches and boll number per plant, 5 combinations showed negative heterobelthosis for plant height while, 6 combinations showed positive heterobelthosis for number of sympodial branches. While 6 combinations showed positive heterosis for number of sympodial branches and number of monopodial branches, 7 combinations showed negative heterosis for cotton yield, ginning turnout and fiber yield.