DDT (dichlorodiphenyltrichloroethane) is a broad-spectrum insecticide, actively used in agriculture and medicine since the 40s of 20th century. In the 70s it became known that DDT is harmful to human health, it remains in the environment and accumulates in the food chain. In 2001, according to the Stockholm Convention, DDT was included in the list of persistent organic pollutants. Decomposition of DDT in the soil is carried out by microorganisms. The most studied are anaerobic bacteria performing the transformation of DDT to DDD and DDE. However, the complete degradation of DDT is possible only under aerobic conditions. It is known a limited number of strains that can degrade DDT under aerobic conditions. The purpose of this research was to study the efficiency of the transformation of DDT by the communities of aerobic bacteria. Association of aerobic bacteria was obtained as a result of a long selection of microorganisms from soils with 40 years long contamination with DDT. The DDT degradation was studied in experiment with washed cells. Bacteria previously were grown in association in mineral medium K1 in 250 ml flasks with biphenyl as a source of carbon and energy. The cells were separated from the medium by centrifugation (centrifuge miniSpin, “Eppendorf ”, Germany), the obtained culture medium was diluted by mineral medium K1 to OD 600 = 2.0. DDT was added to a final concentration of 100 mg/l. Cultivation was carried out at +28°C stirring 120 vol/min (Environmental Shaker-Incubator ES 20/60, "BioSan", Latvia). DDT and possible metabolites were determined by HPLC in the culture medium (chromatograph LC-20A, "Shimadzu", Japan). The experimental results showed that communities of the aerobic bacteria could decompose DDT with varying degrees of effectiveness (Table). The association NK3–31 carries out the complete DDT decomposition into environmentally friendly compounds. After 6 days of incubation, in the medium was observed a possible content of chloride ions, and the full dechlorination of the initial substrate. Only 4-hydroxybenzoic acid was detected as the possible metabolite. The DDT was destructed almost identically by two associations (NK3–2 and NK3–3). However, using NK3–2 association was observed higher content of metabolites and free chlorine ions, than at NK3–3 association; whish indicates the deeper transformation of the initial substrate. The lowest rate of DDT degradation is typical for NK3–1 association. Thus, it reliably was demonstrated the presence in the culture medium of metabolites, previously described as feature characteristic of the strains of the genus Pseudomonas. This work was supported by grant RFBR-Ural number 14–04–96021r_ural_a.