Three acaricidesIndo 50% EC; Challenger 36% SC and Ortus 5% SC were investigated for controlling the phytophagous mites, Tetranychus urticae Koch at Gharbia Governorate on kidney bean plants during 2010 cultivated season. The application of these acaricides induced 94.22, 91.4 and  85.99 % reduction in the population of the tested spider mites, respectively. However, the tested compounds had slightly side effect on the population densities of the associated predacous mites where it gave a reduction percentages of   25.5, 23 and 28.0 % reduction for the same order of the compounds, respectively. The toxic effects of Indo 50% EC on Phytoseiulus persimilis Athias-Henriot biological aspects were evaluated. The obtained results indicated that the different biological aspects (developmental period, longevity and life span) of the predatory mite were decreased with application of acaricide but the fecundity of adult female was significantly increased with Indo applied.