Field experiments were conducted at Sakha Agricultural Research Station  during 1998 and 1999 seasons to study the effect of three irrigation frequencies      (every two, three and four weeks) and three nitrogen levels (40, 60 and 80 kg / Fed) on growth, maturity, yield and yield components of cotton cultivar Giza 85.The results indicated that plant height, length and number of internodes on the main stem, number of sympodia per plant , total dry weight of plant and leaf area were significantly increased as irrigation intervals decreased up to two weeks while number of monopodia / plant tended to increase but the differences were insignificant. Number of open bolls and unopen bolls / plant, boll weight and seed cotton yield per plant and feddan were significantly influenced by irrigation intervals in favor of the close irrigation (every two weeks). The days from sowing date to the first flower appearance and cracking the    first boll were significantly decreased as the irrigation intervals increased. Earliness  percentage was significantly increased by increasing irrigation intervals while position of first sympodium tended to form early by close irrigation intervals.  Consumptive use of water was increased by close irrigation intervals , while water use efficiency was decreased   in the two seasons .  With respect to nitrogen levels the results indicated that this factor had significant effect on most growth traits, as well as number of open bolls per plant,  boll weight and seed cotton yield per plant and feddan. In favor of the high does of nitrogen (80 kg / fed), while unopen boll / fed was insignificantly influenced.  The increase of nitrogen up to 80 kg / fed. caused delaying in maturity as  a result of delaying the formation of the first sympodium which reflected on the appearance of the first flower, cracking of the first boll and earliness percentage. Consumptive use of water and water use efficiency were increased by increasing N levels in both seasons.  The interaction between irrigation intervals and nitrogen levels had significant effect on total dry weight, number of open bolls / plant, boll weight, seed cotton yield per plant and seed cotton yield per feddan in 1998 season. The greatest values of these traits were obtained from the irrigation every two weeks and N application at 80 Kg while the irrigation every four weeks and N levels at 40 kg per feddan resulted low values of these traits.