Three levels of nitrogen 40.60 and 80 kg/fed. were employed with two doses of Pix 11,1-dimethylpiperidinium chloride] (250 and 500 miffed.) plus a non-treated check (water) in 1997 and 1998 seasons. Gin 87 cultivar was used and Pix was sprayed twice at the beginning of flowering stage and 15 days later. Combined data revealed that increasing N level from 40 up to 80 kg/fed. increased final plant height, number of main stem internodeS, sympodia, boll set percentage, earliness percentage, number of open bolls, boll weight, lint percentage and seed cotton yield (kintar/fed), while it decreased main stem internodal length, aborted sites percent‌age and number of unopen boils. N level had no effect on number of monpodia, nodal position of the 1st sympodium and seed index. Comparing with untreated check plants, spraying Pix resulted in decreasing final plant height, number of main stem internodes, monpo‌dia, sympodia, aborted sites percentage and number of unopen bolls/ plant while it increased boll set percentage. earliness percentage, num‌ber of open bolls. boll weight. seed index and seed cotton yield (kintar! fed.). The obtained reductions or increments resulted from Pix spraying were further strengthened as its dose increased from 250 to 500 ml/ fed. Pix treatment had insignificant effect on main stem internodal length and nodal position of the 1st sympodium. The interaction of ni‌trogen level by Pix treatment was not significant for all criteria studied except for seed cotton yield.