The main objective of the present investigation is to obtain wide genetic variation by using lee it tester analysis involving two seeded testers as male parents, namely, AugUraliall and Karashnelry and four Egyptian cotton culbvars as females (lines) namely Gza80, Giza85, Gza90 and Gia87 (G.barbadense). Eight Ft's, the two tester varieties and the four lone cultivars were grown in a randomized complete block design with three replications in 2006 season to evaluate combining abilities and nature of gene action. Genotypes mean squares were highly significant for all traits except for int percentage (L %), lint index (LI) and uniformity index (U.I). Parents mean squares revealed highly significant differences for all studied traits except for lint percentage (L %) and ant index (U). Higher estimates of dominance (02d) variance than additive valance (02A) were recorded and low narrow sense heritability values (h%n.$) and low magnitude of the ratio Q2gCa/Q25ca (less than unity) were found for first fruaing node (FFN), seed cotton yield (KY), lint yield (LY), lint percentage (1%), seed index (SI), lint index (U), micronalr value (Nie), plessly index (PI) and Upper half mean (U.H.M). On the other hand days of first flower (DFF), boll weight (8W) and uniformity index (U.I) recorded lion estimates of additNe variance (02A) and narrow sense heritability (h%n.$). For the testers, Australian and Karashneky varieties were good combiners for first fruiting node (FFN), days of first flower (OFF), seed cotton yield (SCY), lint yield (LY) and uniformity index (VI). Among female parents the variety Giza85 was the best combiner for days of fist flower (OFF), seed cotton yield (SCY), lint yield (LY), seed index (SI) and uniformity index (MI). Giza87 was the best general combiners for fiber traits. Gza90 was the best general combiner for boa weight (avo, seed index (SI) and uniformity index (U.I). Gza80 was the best combiner for first fruiting node (FIN), days of first flower (OFF), boll weight (BW), seed talon yield (SCY), ant yield (LY), micron* value (Mic) and con* index (F1). It oduld be concluded that (tie hybrid (Australian it Giza85) and (Karashneky it Gza85) may be used for the improvement of seed cotton yield (SCY), lint yield (LT), seed Index (SI) and Upper half mean (URA), while (Australian it Gza80) and (Karashneky x Gza80) hybrids were the best for the Improvement of seed cotton yield (SCY), lint yield (1Y) and pressty Index (PI).