The present investigation was carried out at Sakha Agricultural Research Station during 2002 and 2003 seasons of the Egyptian cotton cultivar Giza 88 (Gossypium barbadense L.). The aim of this investigation was to study the effect of water stress and potassium fertilization levels on growth, earliness and seed cotton yield as well as its components. A split plot design with four replication was used. The main plots was assigned to water stress treatments (irrigation intervals) i.e. irrigation every two weeks, every three weeks and every four weeks. Three potassium levels i.e. 0, 24 and 48 K₂O/feddan was assigned in the sub plots. The nitrogen fertilizer was 60 kg/fed. for all treatments.                 The results of this experiments indicated that irrigation interval every two weeks increased final plant height, number of the internodes main stem, both sympodial and monopodial branches, total dry weight number of open and unopen bolls, boll weight, lint % and seed cotton yield per both plant and feddan, while it decreased main stem internode length. Number of days from sowing date to the first flower appearance and the first boll craking were significantly decreased as the irrigation intervals increased. Earliness percentage was significantly increased by increasing irrigation intervals while position of the first sympodium was not affected by irrigation intervals. Leaf area was significantly increased as irrigation intervals decreased up to two weeks.                 With respect to potassium levels the results indicated that plant height, number of internodes per plant, internode length, numbers of monopodia/branch per plant, lint percentage and seed index were insignificantly affected by K rates in the two seasons. On the other hand, number of sympodium per plant, total dry weight per plant, leaf area, numbers of open and unopen boll per plant, boll weight, seed cotton yield per plant and per feddan were significantly increased by increasing potassium fertilizer rates from 24 up to 48 kg K₂O/fed.                 The interaction between irrigation intervals and potassium fertilizer 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 only in 2002 season. The greatest values of these traits were obtained from the irrigation every two  weeks and potassium fertilization at 48 kg K₂O/fed. Seasonal consumptive use incubic meters per feddan and water use efficiency were decreased by expanding the irrigation intervals. On the other hand, consumptive use of water was decreased by increasing potassium fertilizer levels while use of efficiency was increased in the two seasons.