The method for preventing the formation of oil-win-water and/or water-in-oil emulsions and/or for breaking up emulsions already formed, comprises the steps of: (a) adding tensides, materials for increasing viscosity, industrial surfactants, and microorganisms capable of breaking down crude oil components or derivatives and producing at least one type of tenside, to the emulsion already formed or into the device containing the crude oil in which the formation of the emulsion to be prevented, optionally together with additives required for the reproduction of said microorganisms; (b) providing an appropriate temperature for the microorganisms after the addition of the materials listed above; (c) allowing the microorganisms to reproduce and act for a predetermined period of time; (d) checking the results of the treatment; and (e) optionally repeating steps (a) to (d) at least once more, preferably at least three more times.