Field and laboratory studies were carried out to evaluate five soybean varieties, Giza21- Giza 22- Giza 35 Gizalll and Crawford, for their relative susceptibility to the two-spotted spider mite Tetranchus urticae as one of the main pests causing a great damage to soybeans. Obtained data cleared that the peak populations of spider mites occurred during mid of July or during the flowering and pod-formation according to each variety. Crawford& Giza 111 were highly susceptible, respectively. They aggregated 9985 & 8542 mites during the season 2006, while Giza 35 &Giza 21 were highly tolerant at the same trend, which harboring 3418 &4140 mites, but Giza 22 was intermediate. Biological aspects of spider mites affected strongly by soybean varieties, as well as leaves phytochemical components, where as the average period from egg hatching to adult rrnergence which ranged from 5.9 to 9.6 days. Histological studies on leases of soybean variety demonstrated that the more thickness of the cuticle epidermis especially that the lower surface could be considered as a physical tolerance factor against mechanism of spider mites, therefore, it could be recommended that adding potassium fertilizer necessary for different crops.