Two field experiments were carried out in Belcas, Dakhalia governorate, Egypt, during 1998 and 1999 on corn S.C. 10, to study the effect of four irrigation intervals 7, 12, 17 and 22 days, and four N levels, viz 80, 90, 100, 110  kg/fed. And their interaction. A strip plot  design with four replicates was used, where the whole and sub  plots were devoted to the levels of irrigation and N, respectively.                 Results showed that, mostly positive effects were detected  as intervals were shortened and N  levels were increased. The highest yield was observedon  combination gathered irrigation every 12 day with N₁₁₀, which yielded 33.3 and 33.7 ard/fed. in 1998 and 1999, respectively.                 Equilibirity among combinations of the interaction was achieved. A scale was suggested  for classifying studied traits according to their response percentage to the interaction. Such scale included five categories A,B,C,D and E. Days to 50% silking, 100-kernel weight, P% and K% in grains showed high response % category “A", meanwhile, no. of rows/ear showed no response %, category “E". Grain yield/fed. was arranged in “B" category, “medium response". Water use efficiency  seemed to be increased as irrigation interval was shortened.  Water utilization efficiency was  1.09, 1.10,  0.93. 0.82 kg/m³ for intervals 7, 12, 17 and 22 days, respectively.