The aim of the present study was to determine the chemical composition and evaluate the acaricidal activity of Thymus algeriensis essential oil (TAEO) against Varroa destructor. This ectoparasitic mite is a pest of the honey bee Apis mellifera. The essential oil from the, aerial parts of T. algeriensis, obtained by hydrodistillation, was obtained in a yield of 2.8± 0.2%, w/w. The TAEO was analyzed by GC and GC/MS. Thirty-four compounds were identified, representing 99.3% of the oil. The main constituents were carvacrol (48.4%), γ-terpinene (14.9%), p-cymene (14.7%), and thymol (5.6%). Four lots 'were constituted at the level of an apiary in order to study the dynamics of the Varroa destructor and its host, Apis mellifera. After diagnosis by the.biological method "install of diapers", the lots were treated at different doses of TAEO (0.1, 0.3 and 0.5%). TAEO was sprayed on top of the hives. The results show that TAEO at 0.5% resulted in a decrease in the rate of infestation of Varroa destructor, causing a mortality rate of 32.6% without negative effect on the nesting of the queen. The essential oil of T. algeriensis could be used as a bioacaricidal agent.