NOVELTY - Reducing the levels of contamination of soils polluted by a pollutant including 4,4'-dichlorodiphenyltrichloroethane (DDT), 4,4'-dichlorodiphenyldichloroethylene (DDE), 4,4'-dichlorodiphenyldichloroethane (DDD) and/or their isomers, comprises: (i) excavating a soil polluted by the pollutant, sieving the excavated polluted soil to separate out a first part from a second part, adding a first aqueous solution containing enzymes to the first part of sieved polluted soil in reactor, stirring the solid-liquid mass, and separating solid-liquid mass into a residual aqueous suspension and solid part.    USE - The process is useful for reducing the levels of contamination of soils polluted by a pollutant including 4,4'-dichlorodiphenyltrichloroethane, 4,4'-dichlorodiphenyldichloroethylene, 4,4'-dichlorodiphenyldichloroethane and/or their isomers (claimed).    ADVANTAGE - The eco-friendly process simply, rapidly and effectively reducing the levels of contamination of soils polluted by the pollutant with improved biodegradability and without using aggressive synthetic chemicals in a continuous manner, and does not require special devices to avoid further pollution so that the process is economical.    DETAILED DESCRIPTION - Reducing the levels of contamination of soils polluted by a pollutant including 4,4'-dichlorodiphenyltrichloroethane (DDT), 4,4'-dichlorodiphenyldichloroethylene (DDE), 4,4'-dichlorodiphenyldichloroethane (DDD) and/or their isomers, comprises: (i) excavating a soil polluted by at least one pollutant including DDT, DDE, DDD and/or their isomers; (ii) sieving the excavated polluted soil to separate out a first part with particle size measurement less than a predetermined threshold value, from a second part with particle size measurement greater than the predetermined threshold value, where the predetermined threshold value is less than or equal to 100 mm; (iii) adding a first aqueous solution containing one or more enzymes to a predetermined quantity of the first part of sieved polluted soil in a reactor to obtain a solid-liquid mass; (iv) stirring the solid-liquid mass for a predetermined time so that the enzymes catalyze the partial or total degradation of the pollutant by microorganisms present in the polluted soil; and (v) separating the solid-liquid mass into a residual aqueous suspension and into a solid part.