The present investigation was carried out to study heterosis, general and specific combining ability and heritability in broad and narrow sense for cotton fiber quality properties using line × tester design. The study enjoyed eight parents (five lines and three testers) of cotton and their 15 F1 hybrids. Mean squares due to genotypes (parents and their F1 hybrids) were highly significant for fiber finances (F.F.), fiber strength (F.S.), fiber length (F.L.) and uniformity index (U.I.) in F1 hybrids. Line × tester mean squares were highly significant for (F.F.), (F.S.), (F.L.) and (U.I.). The percentage of heterosis relative to mid-parent and better parent of the cross Giza 90 × BBB had recorded the best heterosis (desirable) relative to mid-parent and better parent for (F.S.), (F.L.) and (U.I.) with values (3.71 and 2.09), (4.57 and 2.75) and (1.64 and 0.94%), respectively. In addition, the crosses Giza 90 × BBB and [((G.83 × G.80) × G.89) × Australy] × 10229 had recorded positive and highly significant heterosis for (F.L.) and (U.I.) in F1 hybrids. Results showed that the estimates of broad sense heritability in F1 hybrids for (F.F.), (F.S.), (F.L.) and (U.I.) were high with values 84.024, 89.903, 96.116 and 95.441%, respectively. It be concluded that the previous crosses could be used to produce promising hybrids and expansion the genetic base.