Abstract: In the present study graphic analysis was made for 5x5 diallel cross involving wheat varieties/lines viz., Tobari-66, SARC-1, 4943, 4072 and 4770 to determine genetic mechanism controlling some important yield components during crop season 2001-2002. Number of tillers per plant and grain weight per spike were governed by over-dominance type of gene action while plant height and peduncle length were controlled by partial dominance with additive type of gene action. Whereas, 1000-grain weight exhibited partial dominance type of gene action. Genotype Tobari-66 possessed maximum dominant genes for plant height and peduncle length and SARC-1 for number of tillers per plant. While genotype 4072 had maximum dominant genes for traits like grain weight per spike and 1000-grain weight. Epistasis was absent for all the above mentioned traits. For the traits like plant height, peduncle length and 1000-grain weight, selection in early generation will be fruitful whereas delayed selection should be preferred for the traits like number of tillers per plant and grain weight per spike.