The present research was conducted to evaluate performance and stability of six cotton genotypes included two long staple (variety G86 and promising strain 10229 × G86) and four extra-long staple (G88, G92, promising strains; G77× Pima S6 and G84(G70×51b)×P62. These materials were evaluated for seed cotton and lint yields (k/f), fiber length (mm), fiber strength(g/tex), fiber maturity (%) as well as single yarn strength (cN/tex) with two spinning systems ( ring and compact). Experiments were planted in four locations of the middle and north Delta during the years of 2011 and 2012. Analysis of variance showed highly significant differences for each of year (Y), location (L) and genotype (G) for all traits suggesting the presence of wide range of differences among genotypes and locations. The first order and the second order (Y × L × G) interactions were significant for all studied traits except (Y× G) with seed cotton and lint yields. The overall mean performance for varieties and lines across the eight environments (4 locations x 2 years) demonstrated that Gharbia location was superior to other locations in seed cotton and lint yields and Kafr El-Sheikh came in second rank followed by Damietta, while Dakahlia produced the lowest value. Damietta location was superior to other locations in fiber strength, fiber maturity and yarn strength of both spinning system (ring and compact), while Dakahlia location surpassed the other locations in fiber length. Kafr el-Sheikh location ranked second in the superiority of fiber and yarn traits in all governorates. The long staple promising strain 10229 × G86 surpassed variety G86 in seed cotton and lint yields, fiber strength, degree of maturity and yarn strength of both ring and compact spinning. The extra- long staple G84 (G70×51b) × P62 recorded the highest seed cotton and lint yields followed by variety G92. Variety G92 surpassed all other genotypes in fiber maturity, fiber strength and yarn strength of ring and compact spinning, while variety G88 showed superiority in fiber length followed by strain G77 × Pima S6. The compact spinning system was superior to the traditional ring spinning in single yarn strength for all genotypes under varied environments. The results of phenotypic stability revealed that the promising extra - long staple strain G84 (G70×51b) ×P62 had the highest seed and lint cotton yields, regression coefficient equals to one and the deviation from the regression line did not significantly deviate from zero, so it is characterized by high crop, good stability and convenience for all environments. The strain 10229 × G86 (long staple category) had the highest seed and lint yield and adaptability to different environments. Therefore, these two promising stains are recommended to be developed as new elite cultivars.