Field experiments were carried out to study the efficacy of seven acaricides against the two spotted spider mite Tetranychus urticae kock with refer to their side effect on predaceous mites on soybean plants during 1999 and 2000 seasons in Assiut Governorate.                 The obtained results clearly showed  that all tested materials gave over 90% mortality of spider mite population after three days of spray, but in different trend.  Residual activities on spider mites could be arranged in descending  order as follows; vertimec, Endo, Ortus, Sunmite, propergate, neoron and Dicofol, while the side effect of tested materials on predator mites cleared that vertimec gave the highest mortality, followed by neoron, endo, sunmite, ortus,  dicofol and propergate, percentages of reduction being 39.96, 39.92, 38.03, 36.50, 34.64, 33.70 and 31.87% respectively.