The population fluctuations of Tetranychus urticae Koch and the associated phytoseiid mite, Euseius scutalis (A.-H.) on three soybean cultivars at Gharbia Governorate were studied during two successive seasons of 2015 and 2016. The results indicated significant differences in the T. urticae infestations through 2015 and 2016 seasons. Giza 35 variety harbored the highest infestation recorded 552.56 and 440.5 motile stages/10 leaflets for the two successive seasons, as compared with Giza 21 and Giza 83 varieties. Giza 21 variety was the most tolerant one recorded 130.38 and 174.88 motile stages/10 leaflets for two successive seasons. Significant positive correlations occurred between the T. urticae population and E. scutalis in all soybean varieties. The predatory mite was the main important predator for suppressing population density of T. urticae population during the two successive seasons. The insignificant positive effect of maximum and minimum temperatures on the population of T. urticae infested the three soybean varieties during 2015 and 2016. The combined effect of the tested weather factors (max temp., mini temp. and R.H. %) and the plant age together on T. urticae population were studied. The plant age and phenology were more effective on T. urticae population as compared with the weather factors.