The lethal effect of five acaricides alone or mixed individually with ten separate fertilizers, on the phytophagus mite Tetranychus urticae, was evaluated after 72 hours under laboratory conditions of 30 °C 5 and R. H. 70 % ± 5. The tested acaricides were fenpyroximate (Ortus 5% EC), ethion (Endo 50% EC), abamectin (Vertimec 1.8% EC), chlorfenapyr (Challengers 36% SC) and hexythiazox (Maccomite 10% WP). Used fertilizers were potassium sulphate, ferrous sulphate hepta hydrate, magnesium sulphate hepta hydrate, zinc sulphate hepta hydrate, ammonium sulphate, ammonium nitrate, calcium nitrate, di ammonium phosphate, phosphoric acid and urea. LC₉₅ values of the previous acaricides singly were 422.8, 2112.9, 6, 0.9 and 363.6 p.p.m., respectively. LC₅₀ values of the previous acaricides singly were: 329.8, 1851, 5.5, 0.4 and 259.6 p.p.m., respectively. The recommended doses of the previous acaricides were 1.5, 0.8, 72.8, 1007.6 and 0.8 fold of LC₅₀ values of these acaricides, respectively. Potassium sulphate had a synergistic effect on each of Ortus and Vertimec, but had an antagonistic effect on Endod, Challenger and Maccomite. Each of ferrous sulphate hepta hydrate, magnesium sulphate hepta hydrate, zinc sulphate hepta hydrate, ammonium sulphate, ammonium nitrate, calcium nitrate and di ammonium phosphate had an antagonistic effect on all the examined acaricides. Phosphoric acid had a synergistic effect on Ortus only but had an antagonistic effect on the rest tested acaricides, Urea had a synergistic effect on Ortus and Challengers but had an antagonistic effect on the rest acaricides.