Four promising Egyptian cotton genotypes were evaluated compared with the four commercial cultivars grown in seven different locations in lower Egypt during five successive seasons from 2007 to 2011. Randomized complete block design with four replications was used at each location. The traits studied were seed cotton yield (k/f), lint yield (k/f), boll weight, lint percentage, seed index and lint index. Highly significant differences between genotypes, locations, seasons and the interaction between locations by seasons were obtained for yield and yield components traits. The effect of the interaction between genotypes by locations, genotypes by years and the second interaction were highly significant for all studied traits. The results showed that the extra long staple promising strain [G.84 (G. 70 × G. 51 b)] × Pima 62 and the new variety of the same category Giza 92 produced the highest values for yield and most yield components traits than the commercial cultivar Giza 88. Also, the extra long staple promising strain (G.77 × Pima S6)surpassed the commercial cultivar Giza 87 in most studied traits. From the results, the long staple promising strain (10229 × G.86) exceeded the commercial cultivar Giza 86 in all studied traits. Adaptation to different environments was high for the promising strain of extra long staple [G.84 (G. 70 × G. 51 b)] × Pima 62 and the commercial cultivar of the same category Giza 92 at El-Gharbia governorate for most traits. The promising strain of long staple (10229 × G.86) exceeded the commercial cultivar Giza 86 for all studied traits at El-Sharkia governorate. Therefore, it seems necessary to continue evaluating new cotton genotypes by growing them at several locations over an adequate number of years before recommending any variety for acertain location