Two experiments were carried out at Sakha Agricultural Research Station , Cotton Research Institute , to study the effect of drought on morphological , yield , yield components and physiological traits in some cotton cultivars . This study comprised some Egyptian cotton cultivars i.e. G.91, G.89, G.85, G.88, G.70, G. 89x G.86 , G.89 x Pima S6, G.86 and G.80. Were  planted under drought condition which toke five once irrigation and normal condition, which toke eight once irrigation as control . The results obtained could be summarized as follows :- 1-  Cultivars differently responded to drought conditions. 2-  Drought condition tended to decreased number of fruiting branches ,   dry weight , plant height , leaf area index, boll weight , seed and lint cotton yield per plant , seed index , lint percentage , number of bolls per plant , total chlorophyll , proteine and oil percentage in seeds. 3- The proline content in leaves was increased as a result of water stress conditions (drought) . 4-  G.86 and G.80 observed the highest values of content of proline in leaves and had a highest  yield and its components under drought stress. 5-  For plant breeder , these results very important to select plants had higher proline content in leaves as indicator to obtained plants more tolerant to drought and highly yielding .