Nine Genetic Male Sterility based diploid cotton hybrids along with parents and checks were evaluated during Kharif 2009-10 at Main Agricultural Research Station, Dharwad to estimate the level of heterosis. The analysis of variance revealed that the parents and hybrids differed significantly for all the characters under study indicating presence of considerable genetic variability between the genotypes. The Genetic Male Sterility based hybrids exhibited higher level of heterosis over mid parent, better parent and standard ckeck for seed cotton yield and its component traits and for fibre quality characters. The two inter specific crosses MSD 7 nor x RAhS-14 and MSD 7 nor x Jayadhar were found to be highly heterotic among all for seed cotton yield, number of sympodia, number of bolls per plant and ginning out turn. For fibre quality traits crosses MSD 7 nor x RAhS-14, MSD 7 nor x DDhc-11, MSD 7 nor x ARBH -35, MSD 10 x RAhS-14 and MSD 11 x DLSa-17 were found to be promising.