Late wilt and northern leaf blight of maize are the most important diseases in Egypt. Inbred lines combining ability and its interaction with environment are required information to get superior hybrids for grain yield and resistance to late wilt and northern leaf blight diseases. Nine white maize inbred lines were crossed in a half diallel mating design at Sakha Research Station in 2021 season. The 36 resulted crosses were evaluated in two trials in 2022 season. In the first trial, 36 F1 hybrids plus two checks were evaluated at Sakha, Sids and Mallawi Agricultural Research Stations for traits, days to 50% silking, plant height, ear height, number of ears/plant, grain yield, ear length and ear diameter, while in the second trials, 36 F1 were evaluated under three nitrogen levels in a diseases nursery under artificial infection conditions by late wilt and northern leaf blight diseases at Sakha Research Station to estimate percentage of resistance to both diseases. Highly significant differences were detected among three locations in the first trial and between three nitrogen levels in the second trial. The mean squares due to general and specific combining ability were significant or highly significant for all traits, except mean squares due to specific combining ability for plant height, ear height and ear length in the first trial and northern leaf blight in the second trial. The desirable inbred lines for general combining ability effects were Sd41 and Ism77 for earliness, short plant and low ear height, Sd4, Sd7 and Sk13 for increased number of ears/plant, Sk5001, Sk5004, Sd41 and Sk13 for increased grain yield and ear length, Sk5001 and Sk5004 for increased ear diameter and Sk5005, Sd41, Sd7 and Ism77 for resistance to late wilt disease and Sk5001 and Sd41 for resistance to northern leaf blight disease. The desirable hybrid for specific combining ability effects was (Sd4×Ism77) for earliness, short both plant height and ear height, (Sd1121×Sd7) for number of ears/plant, (Sk5001×Sd7) for grain yield, (Sd4× Sd1121) for ear length, (Sk5004×Sd7) for ear diameter, (Sk5001×Sd1121) for resistance to late wilt disease and (Sk5001 ×Sd13) for resistance to northern leaf blight disease. The hybrids which had high grain yield and resistance to late wilt and northern leaf blight diseases were (Sk5001×Sk5004), (Sk5001×Sd41), (Sk5004×Sd7), (Sk5004×Sd41), (Sd41×Sk13) and (Sd7×Sk13). These hybrids will be evaluated in the advanced level of testing in maize breeding program.