Combining ability and heterosis analysis was done to identify the potential parents and best performing hybrids for seed cotton yield, yield contributing traits and fiber quality parameters. Six lines, viz., VH-259, IUB-222, CRS-456, AA-703, KZ-191, PB-39 and four testers PB-39, CIM-608, BH-163 and PB-900 were crossed in line × tester crossing fashion to develop 20 F1 hybrids. Analysis of variance displayed significant differences among parents and hybrids indicating the presence of genetic variability except fiber fineness. δ2GCA/δ2SCA ratio depicted the predominance of non-additive types of gene action for plant height, number of monopodial branches, number of sympodial branches, numbers of bolls, boll weight, seed cotton yield, lint percentage, fiber length and fiber strength. The parents VH-259, CRS-456 and AA-703 among lines and PB-39 among testers displayed significant GCA effects for most of the traits. VH-259 × PB-39, CRS-456 × CIM-608 and AA-703 × PB-900 registered significant SCA effects and positive heterosis and hetrobeltiosis for most of the trait investigated.