Olive bud mite, Aceria oleae (Nalepa, 1900) (Acari: Eriophyidae) is one of the key pests that regularly needs control with acaricides in olive orchards of Bursa Province, Turkey. For the chemical control of A. oleae, it is critical the use of acaricides does not reduce the survival and fecundity of its natural enemies. The toxic effects of three concentrations of seven acaricides were assessed against both A. oleae and its predator Neoseiulus californicus (McGregor, 1954) (Acari: Phytoseiidae) using a residual method under controlled conditions at Bursa Uludağ University during 2020-2021. The highest recommended concentrations of acequinocyl, azadirachtin, fenbutatin oxide, milbemectin, pyridaben, spirodiclofen and sulfur killed A. oleae adults with rates varying from 80 to 100%. Two concentrations of milbemectin, pyridaben and sulfur showed high mortality rates. Nevertheless, highest recommended concentrations of acequinocyl, pyridaben, spirodiclofen and sulfur were found to be highly toxic to N. californicus adults with rates varied from 82 to 100%. The high mortalities for mobile immature stages and reducing in the fecundity of N. californicus occurred by highest recommended concentrations of all tested acaricides. Based on the scale recommended by the International Organization for Biological Control, some sublethal concentrations of fenbutatin oxide, spirodiclofen and sulfur were found to be slightly harmful to both mature and immature of N. californicus.