The present study was carried out to obtain information about the performance of maize inbred lines, genetic diversity, gene action and assessment of the combining ability of parental lines and their F1s by using diallel fashion. Cob length, number of kernels/row and no. of grains/cob could be the important selection criteria in the improvement of maize lines and hybrids for higher grain yield. The average inter-cluster was always higher than the average intra-cluster distance suggesting wider genetic diversity among the inbred lines of the groups. From Wr-Vr graph it has been noticed that expression of dominant and recessive alleles in the parents was influenced by environment as the same parent showed different positions on graphs. From this study, it is concluded that parents with recessive and dominant genes can also contribute towards high yield. Only 5 crosses had higher grain yield. Of these crosses, P1xP2, P2xP5, P4xP5 and P5xP6 were considered promising hybrids and will be tested in yield trials for further evaluation.