Three field experiments in split-split plot design were carried out at Agriculture Research Center, Shandweel Research Station, Sohag Governorate, during the summer seasons 2010, 2011 and 2012 on clay loom soil to evaluate the effect of foliar spray of humic acid (4 cm³ /L) at 30 and 45 days from sowing, under three levels of nitrogen fertilizer (0, 90, and 120 kg N/fed.) on plant growth parameters, some biochemical and mineral contents (NPK) in leaves and grains of two maize hybrids (Single cross Pioneer 30K09 and Three way cross-310). Results showed that S.C. Pioneer 30K09 hybrid surpassed T.W.C.-310 hybrid in the values of P_N , E and G_s as well as N and K-content in leaves and grains, while T.W.C.-310 hybrid surpassed S.C. Pioneer 30K09 hybrid in the values of crude protein content in grains, P-content in both leaves and grains also in N-content in grains, however there were no significant differences between the two maize hybrids in respect to chlorophyll, dry weight, leaf total carbohydrate and grain oil contents. There were gradual and significant increases in all parameters by increasing nitrogen fertilizer dose, the most effective dose of nitrogen fertilizer was 120 kg N/fed. for the most traits, while, application of 90 kg N/fed. led to significant and highest values of P_N , E and G_s, also, P and K-content in leaves and K-content in grains. Thus, it could be concluded that foliar spraying with humic acid combined with adding 90 kg N/fed. gave higher values of all criteria than those obtained by only the recommended dose (120 kg N/fed). Moreover, the two examined hybrids responded to spraying HA under 120 kg N/fed. comparing with their values at the recommended dose only.