Abstract: Stability in yield of seed cotton over wide range of environments has long been desired by plant breeders. To determine the possible effects of environment and genotypic differences for yield, three advanced strains/genotypes of cotton viz. AEHM-4/4/89, AEH-2/90, AENB-10/87 alongwith two commercial checks viz., NIAB-78 and Rehmani were tested over different environments in Sindh. Genotypes, locations and genotype x environment (GxE) interactions were highly significant (P≤ 0.01) indicating genetic variability between genotypes by changing environments. Stability parameters calculated were regression coefficient (b), S.E. and deviation from regression (S2d). Genotypes, AENB-10/87, NIAB-78 and AEH-2/90 had the highest mean seed cotton yield, regression coefficient (b) less than or close to unity (0.749, -0.295, 0.215, respectively), the lowest deviation from regression (S2d) (0.083, 0.025, 0.071 respectively) suggesting above average stability and adaptability over environments. AEHM-4/4/89 and commercial check Rehmani produced low mean yields than the grand mean with the highest regression coefficient (b) and the highest deviation from regression coefficient (S2d) had below average stability and are specifically adapted to favourable environments.