The current study was carried out at Cairo University Experimental Farm during the summer seasons of 2004 and 2005 as a first step to broaden the Egyptian cotton genetic base and initiate a practical genetic foundation to improve some important traits like fitting to machine harvesting. The study utilized the F₁ crosses to investigate the main performance variation, heterotic effects and anatomical differences for growth, earliness and yield characteristics of inter and intraspecific cotton crosses resulted from 5X5 set of half diallel crossing design. The original parents weretaken from a three years-selfed individual plants. The anatomical measurements were done on the eleventh internode of the main stem and on the corresponding leaf of the parents; Giza 89, Pima 6, Giza 85, Wild and Tamcot as well as some of their selected crosses; Giza89 X Pima6, Giza89 X Wild, Pima6 X Giza85 and Giza 85 X Tamcot at flowering stage.  Compared to their parents, the main stem diameter was larger in F₁ hybrid plants (Giza 89 X Pima 6, Pima 6 X Giza 85, Giza 89 X Wild and Giza 85 X Tamcot).  All included tissues (thickness of epidermis, cortex, vascular tissues and parenchymatous area of the pith) shared to different extents in increasing the thickness of stem diameter of F₁ hybrid plants. The increment in cortex thickness was attributed to the increase in cell size and number of cell layers. The larger thickness of vascular cylinder was due to the larger amount of conducting elements; phloem and xylem tissues. The cambial activity was obviously stimulated since wider phloem and xylem tissues were produced. Moreover, xylem vessels had wider cavities which amounted to more total active conducting area to cope with vigorous growth produced by such types of F₁ cotton crosses plants. Likewise, the leaf lamina in F₁ hybrid plants was thicker than that of their original parents. Both of the palisade and spongy tissues as well as leaf midvein were increased in thickness and the midvein bundle was increased in size. A trend of improved earliness and yield variables were observed in the inter-intraspecific crosses, since significant heterotic effects were found over mid parent and high parent for the majority of the studied traits with slight magnitude. In addition to the crosses G89XP6, P6XG85, P6Xtamcot and G85Xtamcot, the study comprehensively showed that the mean performance of G89-based crosses array appeared to progress satisfactorily among all hybrids arrays for the most traits. This result is important too, since the majority of the genetic constitution of the hybrids of these crosses can be revealed belonging to barbadense group. This may accelerates the attainment of the breeding objectives through reducing the required trait fixation steps in the breeding programmes, meanwhile reduce the expected backwardness and lint deterioration that might be happened thru exploiting some hirsutum germplasm. Thus, the study has a tendency to suggest these crosses for further breeding studies and selection in the subsequent segregating populations to improve Egyptian cotton and looking for a cotton genotype can be mechanically harvested.