Field experiments were carried out at farm of Research Center of Agriculture, Mallawy, EL-Minia Governorate, Egypt, during the two successive Autumn seasons of 2003 and 2004 . Squash Cv. "Eskandrany" was selected to study the influence of chemical N rates . organic manure and biofertilizers on yield of squash. Treatments were arranged in split split - plot design in complete randomized block with four replicates. Chemical N rates ( 0.0, 30, 45 and 60 kg N / fed. ) treatment were arranged at random in the main plots .Three organic manure treatments (untreated, chicken manure and sheep manure) were distributed at random in the sub-plots, while three biofertilizer treatments (untreated, T26, T16 )  were distributed at random in sub-sub-plots. All flowers parameters significant affected by chemical N rates and biofertilizers. All interactions among the studied factors had significant effect on flower characters. All yield parameters were significantly affected by the chemical N rates in both seasons, where 45 Kg. N / fed. was obtained the highest value of early yield (kg) / plant , while there is no different between 60 kg N / fed. and 45 kg N / fed. on number of fruits ,average weight of fruit (g.) and total yield (ton/fed.) . NO₃ and NO₂ concentrations were significantly affected by the chemical N rates in both seasons. T26 decreased NO₃ and NO₂ concentrations.