This study was performed during the two summer seasons 1999 and 2000. Full diallel crosses of four yellow maize inbred lines were conducted. The aim of this study was to determine the relationship of various inbred anatomical characters with single cross performance, and high yielding inbred through its anatomical features as criteria to plan crosses for all single and double hybrid combinations. Inbred lines and hybrids mean performance and heterotic effects, general and specific combining ability, reciprocal effects, as well as variance components for anatomical characters were determined. Results suggested that flint inbred lines are characterized by high counts for number and size of bundles of the outer zone periphery to the epidermis, the size of bundles in the central region of the stem, thickness and number of cells of the sub-epidermal sclerenchymatous tissue and number of vascular bundles per microscopic field. While, dent inbred lines are characterized by large size of both metaxylem vessels and ground tissue parenchymatous cells. The cross L₁x D₁ showed heterosis over the better parent for most characters under investigation. Relative to inbred parents, the average dimension of the inner vascular bundles and the average size of parenchyma cells of the ground tissue were higher than those of parents. On the contrary, number of vascular bundles per microscopic field was greater in parental lines. The increase in bundle size that characterized hybrids led to the decrease in their number. As hybrids were characterized by grater sized vascular bundles and ground parenchymatus cells as compared with those of inbred lines. The thicker vascular bundles were accompanied by a considerable increase in vessel dimensions.           Reciprocal mean square of epidermis thickness, average diameter of ground tissue cells and vascular bundle dimensions at the outer zone were higher than that of general combining ability (GCA) and specific combining ability (SCA) indicating the importance of maternal effects in the inheritance of such traits. However, both GCA and SCA were more or less equals, suggesting that, both additive and dominance gene effects were involved in the inheritance of such character. On the other hand, the parental inbred line D₁ exhibited the highest value for general combining ability for sub-epidermal sclerenchymatous tissue, the average size of and ground tissue cells in the inner zone and number of vascular bundle per microscopic field. Thus, it would be preferable as a parent in breeding for such traits. The cross D₁ x L₂ were of highly significant values for the above mentioned characters. There was significant variance, due to additive alleles (Ď), for number of vascular bundles in a microscopic field, vascular bundle dimensions at the inner zone and average diameter of ground tissue. Dominance effects overall heterozigous loci (h²) were highly significant. The estimated F values showed non-significant values revealing excess of dominant alleles related to inheritance of the following anatomical characters; vascular bundle dimensions, average diameter of ground tissue at the inner zone, vascular bundle dimensions at the outer zone and thickness of sub-epidermal sclerenchymatous tissue. Over dominance is suggested for average number of vascular bundles in both outer and inner zone of the stem.