Technological processes for the synthesis of composite systems based on bovine (rather than synthetic) hydroxyapatite are rarely described. That’s why the influence of the heat treatment medium on the properties of the composite system bovine hydroxyapatite/magnetite (BHA/Fe3O4) obtained using physico-mechanical and chemical methods were investigated. It was established that the most efficient medium for heat treatment of studied materials is vacuum. Due to XRD analysis data allow us to assert that the most perfect lattice is formed with the use of the chemical method for production and heat treatment in a vacuum (crystallinity 86%), and the least perfect one is formed by the mechanical method for production and heat treatment in a nitrogen medium (71%). The method for adding magnetite has only a minor effect. Investigated conditions of heat treatment of composite systems BHA/Fe3O4 promoted obtaining optimal magnetic properties and stable behavior in experiments in vitro. Keywords: bovine hydroxyapatite, magnetite, crystallinity, specific saturation magnetization, in vitro experiments.