The present study was carried out at Shandaweel Agricultural Research Station during 2009 and 2010 seasons to study the effect of water stress and nitrogen fertilization levels with boron foliar application on growth, seed cotton yield and its components of Giza 90 (Gossypium barbadense L.). A split-plot design with four replications was used. The main plots were assigned to water stress treatments (irrigation every two weeks and three weeks). Nitrogen fertilization levels with boron foliar application i.e., 60 kg N/fed, 60 kg N/fed + foliar spraying by boron (at budding stage beginning), 60 kg N/fed + foliar spraying by boron (at flowering stage), 60 kg N/fed + foliar spraying by boron (at budding stage beginning and flowering stage), 75 kg N/fed, 75 kg N/fed + foliar spraying by boron (at budding stage beginning), 75 kg N/fed + foliar spraying by boron (at flowering stage) and 75 kg N/fed + foliar spraying by boron (at budding stage beginning and flowering stage) were assigned in the sub-plots. The results indicated that irrigation every two weeks significantly increased plant height at harvest, number of fruiting branches/plant, number of open bolls/plant, boll weight and seed cotton yield/plant in both seasons, while, days to first open boll, seed cotton yield/fed, days to first flower appearance and location of first fruiting node (in one season only). However, number of plants at harvest was not significantly affected by water stress in both seasons. With respect to nitrogen fertilization levels and foliar spraying with boron treatments, the results indicated that, plant height at harvest, number of fruiting branches/plant and seed cotton yield/feddan were significantly increased by 75 kg N/fed + foliar spraying by boron (at budding stage beginning and flowering stage) in both seasons, while, boll weight (in 2009 season only), meanwhile, boll weight (in 2010 season only) by 75 kg N/fed + foliar spraying by boron (at budding stage beginning). However, number of open bolls/plant and seed cotton yield/plant (in 2009 season only) by 75 kg N/fed + foliar spraying by boron (at flowering stage), while, number of open bolls/plant and seed cotton yield/plant (in 2010 season only) by 75 kg N/fed. Meanwhile, location of first fruiting node and number of plants at harvest/fed were not affected by nitrogen fertilization levels + foliar spraying with boron in both seasons. It could be concluded that using regular irrigation intervals every two weeks along the whole plant life and nitrogen application 75 kg N/fed + foliar spraying with boron (at budding stage beginning and flowering stage).