Two field experiments were conducted at the Experimental Farm of Faculty of Agriculture (Saba Basha), Alexandria University, Egypt during 2017 and 2018 seasons, to study the response of the three maize hybrids productivity to different combination between nitrogen and potassium fertilizer and its effect to infection by fungal diseases. Split plot design with three replications was used, where the main plots occupied by three hybrids of maize (S.C.10, S.C.131 and T.W.C.321), meanwhile the subplots contained combination between nitrogen and potassium fertilizer forms (192 kg N/ha + 0 kg K/ha, 192 kg N + 57.6 kg K/ha, 192 kg N + 115.2 kg K/ha, 288 kg N/ha + 0 kg K/ha, 288 kg N + 57.6 kg K/ha, 288 kg N + 115.2 kg K/ha, 384 kg N/ha + 0 kg K/ha, 384 kg N + 57.6 kg K/ha, and 384 kg N + 115.2 kg K/ha). Each subplot consisted of 6 ridges 3.50 m in length and 70 cm in the width and plot area was 14.7 m². The results revealed that maize hybrids differed significantly and combination between nitrogen and potassium fertilizer affected significantly in plant height (cm), ear length, number grains/row, number of grains/ears, 100- grain weight, grain, straw, and biological yield (kg/ha.) as well as harvest index %. The results indicated that there was significant effect of fertilization levels on yield, its components and leaf blight infestation of some maize hybrids where fertilizing maize hybrid TWC321 by 288 kg N + 57.6 kg K/ha recorded the highest values of yield and its components, on the other hand, the maize hybrid TWC321 recorded the highest yield and high tolerant for leaf blight under Alexandria conditions.