The present investigation was carried out to study heterosis, general and specific combining ability and heritability in broad and narrow sense for yield and yield component traits using line × tester analysis design for 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 all studied traits revealing a large amount of variability among them. Results indicated that the cross (No. 1) had displayed the best heterosis (desirable) relative to mid-parent and better parent for (L. %) with values 7.76 and 7.25%. While, the cross (No. 4) had showed the best heterosis (desirable) relative to mid-parent and better parent for (S.I.) and (L.I.) with values 10.31, 9.15, 18.04 and 15.77%, respectively. In addition, the estimates of (G.C.A.) effects for (No.O.B. / P.), (B.W.), (S.C.Y. / P.) and (L.Y. / P.) were positive and highly significant in line (L₅) in F₁ hybrids. In addition, the cross (No. 12) in F₁ hybrids had showed positive and highly significant for (No.O.B. / P.), (B.W.) and (S.C.Y. / P.). Results clarified that the estimates of broad sense heritability in F₁ hybrids for (No.O.B. / P.), (B.W.), (S.C.Y. / P.), (L.Y. / P.), (L. %), (S.I.) and (L.I.) were moderate to high with values 96.25, 96.04, 97.35, 93.09, 54.70, 97.42 and 41.49%, respectively.