The effect of three irrigation intervals (every two, three and four weeks, started after first irrigation), three nitrogen levels (40, 60 and 80 kg/fed.) and their interaction on both vegetative and fruiting growth, earliness measurements, dry weight and seed cotton yield and its com­ponents, were studied in two experiments conducted at Sakha Agricultural Research Station during 1996 and 1997 seasons using Giza 87 cotton cultivar. In both seasons, irrigation cotton every two weeks throughout the season resulted in higher number of main stern inter-nodes, monopodia, sympodia, both fruiting and aborted sites, boll reten­tion, both vegetative and fruiting parts dry weight, total plant dry weight, number of open bolls, boll weight, lint percentage, seed index and seed cotton yield (Kentar/fed.). Final plant height and main stem in­ternodal length reached the maximum with the intermediate interval (irrigation every three weeks), while they were restricted with wide and close irrigations, respectively. On the other hand, close irrigation mini­mized root dry weight and delayed maturation in terms of raising nodal position of the fist sympodium, increasing number of days to first open flower and boll and decreasing earliness percentage. Regarding nitrogen rate treatments, the highest level (80 kg N/fed.) increased final plant height, number of main stem internodes, monopodia, sympodia, fruiting sites, aborted sites, boll retention, dry weight of vegetative and fruiting parts and root system, total dry weight number of open bolls, boll weight, lint percentage, seed index and seed cotton yield (Kentar/fed.). Conversely, increasing introgen levels delayed maturation as presented by higher nodal position of the first sympodium, days to both first open flower and boll and lower earliness percentage. The interaction of irriga­tion intervals and nitrogen rates had insignificant effect on all traits un­der study.