A half diallel cross among 9 inbred lines of maize (Zea mays L.) was evaluated under two locations (Fac. Agric. Moshtohor and Quesna menofiya Governorate) for some quantitative characters; i.e. Days to 50 % tasseling, plant height, No. of rows/ear, No of kernels/row,100-kernel weight and grain yield/plant. General and specific combining ability were estimated according to Griffings (1956) diallel cross analysis designated as method 2 and 4 model 1 for each location as well as the combined over them. Locations mean squares were significant for all studied traits, except for no. of rows/ear, in both methods, with mean values in L1 being higher than those in L2 for all traits in both methods of analysis (M4 and M2), except no. of days to 50% tasseling. In both methods, genotypes mean squares were significant for all traits in both locations as well as the combined analysis. The mean squares due to general and specific combing ability were highly significant for all studied traits in both methods and both locations as well as the combined analysis. In the method 4, high of GCA/SCA ratios which largely exceeded the unity were obtained for all studied traits in both locations as well as the combined analysis, except days to 50% tasseling at L2 only. In method 2, no. of rows/ ear at L2 had GCA/SCA ratio equal unity. High ratios which largely exceeded the unity were obtained for days to 50% tasseling, 100-kernel weight and grain yield/ plant in both locations and the combined analysis. This finding coincided with that already reached from the combining ability analysis of Griffing method-4. For the other remain cases, GCA/SCA ratios, were less than unity. The mean squares of interaction between locations and both types of combining ability were significant for all traits in both methods of analysis. The parental inbred lines no. 9, 1 and 8 seemed to be good combiners for yield and some of its components in both methods of analysis. The crosses P1xP4, P1xP8, P1xP9, P4xP7, P6xP9 and P8xP9 showed the highest values for SCA effects for grain yield and its components in both methods of analysis.