The present investigation was carried out at Shandaweel Agriculture Research Station during 2005 and 2006 seasons to study the effect of NPK application levels on growth and seed cotton yield as well as its components of the Egyptian cotton cultivar Giza 90 (Gossypium  barb dense L.). A randomized complete blokes design with four replicates was used. Nine treatments were as follows: NPK₀ : 45 kg N   + 15 kg P₂O­₅       + 0 kg K₂O/ fed NPK₁ : 45 kg N   + 22.5 kg P₂O­₅  + 24 kg K₂O/ fed NPK₂ : 45 kg N   + 30 kg P₂O­₅        + 48 kg K₂O/ fed NPK₃ : 60 kg N   + 15 kg P₂O₅     + 0 kg K₂O/ fed        NPK₄ : 60 kg N   + 22.5 kg P₂O₅  + 24 kg K₂O/ fed NPK₅ : 60 kg N   + 30 kg P₂O­₅     + 48 kg K₂O/ fed NPK₆ : 75 kg N   + 15 kg P₂O­₅     + 0 kg K₂O/ fed NPK₇ : 75 kg N   + 22.5 kg P₂O­₅  + 24 kg K₂O/ fed NPK₈ : 75 kg N   + 30 kg P₂O­₅     + 48 kg K₂O/ fed                 The results of  these experiments indicated that plant height at harvest, Number of fruiting branches/ plant, height of fruiting nodes, number of open bolls/ plant, boll weight, seed cotton yield/ plant and feddan were significantly increased by tested treatments in both seasons. The greatest values of these traits were  obtained from the combined fertilization with 75 kg N + 30 kg P₂O₅ + 48 kg K₂O­/fed.