Two experiments were carried out at Shandweel Agric. Res. Station during 2003 and 2004 seasons to study the effect of population densities: i.e. 64600, 51700 and 43100 plants/faddan (20, 25 and 30 cm between hills) and nitrogen levels (45, 60 and 75 kgN/faddan), as well as their interactions on growth, yield and yield components of cotton cultivar Giza 90.             The results indicated that increasing plant population Produced the best values of the first fruiting branch node, number of plants/feddan at harvest and seed cotton yield/faddan. However, the plant height at harvest had significantly increased by increasing population density in 2003 season only. In the contrary, decreasing population density led to a significant increase in number of fruiting branches/plants, number of open bolls/plant, boll weight and seed cotton yield/plant in both seasons.             As for nitrogen levels, the plant height at harvest, number of fruiting branches/plant, number of open bolls/plant and seed cotton yield/plant increased significantly by increasing nitrogen levels in both seasons. However, the location of the first fruiting branch node and boll weight increased significantly by increasing nitrogen application in 2004 season only. While, seed cotton yield/faddan increased in 2003 season only. The interaction between population density and nitrogen levels had significant effect on seed cotton yield/plant in both seasons, and, plant height at harvest and seed cotton yield/faddan in 2003 season only. While, the effect on location of the first fruiting branche node, number of open bolls/plant and boll weight was affected in 2004 season only. Meanwhile, interaction between the two factors had insignificant effect on number of fruiting branches/plant in both seasons. It could be concluded that there was a response of Giza 90 cotton variety to population density (64600 plant/fad.) and nitrogen application up to 60 kg N/fad. (2003)  and application of 75 Kg N/Fad. (2004), with an average yield of 11.58 and 11.23 K/fad. For 2003 and 2004 seasons respectively.