A complete diallel cross between five maize inbred lines viz; Elp-326, Elp-433, Elp-612, Elp-326 and Elp-780 was used to determine the genetic behavior of grain yield, days to 50% tasseling, days to 50% silking, plant height, cob height and cob girth during growing seasons 2018 and 2019. Analysis of variances was carried out for all the parameters following (Steel, R.G.D., & Torrie, J.H. 1980) technique which revealed highly significant differences for all the traits studied. The analyses of GCA and SCA were carried out using (Griffing, B. 1956) technique, Method I, Model II. Both GCA and SCA mean squares were highly significant for all the traits indicating the involvement of additive as well as non additive gene interactions in the expression of these traits. SCA mean squares and variances were larger than those of GCA mean squares and variances which suggested that non additive genes had major role in the inheritance of grain yield and its related characters under study. Elp-433 was found the best general combiner for all the parameters. Elp-426, Elp-326 were good general combiners for grain yield only. Elp-326 x Elp-780 and Elp-426 x Elp-433 were best combinations for grain yield and most of its components. The crosses Elp-780 x Elp-433, Elp-780 x Elp-426, Elp-780 x Elp-433, Elp-326 x Elp-433, Elp-612 x Elp-426 and Elp-326 x Elp-612 having higher reciprocal effects pointed out that partial role of cytoplasmic inheritance cannot be ruled out in controlling the physiology of these traits.