A four-parent diallel cross (including reciprocals) of grain sorghum (Sorghum bicolor [L.J Moench) was analyzed for grain yield and protein percent. Differences among parents indicated the presence of additive component of genetic variation for both characters. Dominal~e was observed in the direction of higher yield and lower protein percent. The. positive and negative alleles were equally frequent for yield, while for protein percent, the negative alleles were more frequent. Apparently improvement of protein percent would require selection for recessive alleles having a low frequency, whereas improvement of yield needs both alleles. Number of genes for grain yield was three and at least eight for protein percent. Grain yield heritability was high (93%), indicating effectiveness of selection for this trait, while that of protein was moderately (55%). Phenotypic correlation coefficient between grain yield per plant and protein percent showed negative value (-0.06).