A number of microorganisms in activated sludge in the process of waste water treatment were used for accumulating polyhydroxyalkanoates(PHA). Mixed bacteria and organic carbon source were used in microaerophilic-aerobic treatment of activated sludge and some cultural conditions: oxygen supply rate, attachment carbon source concentration and culture time were investigated. The PHAs obtained appeared a mixture of copolymers or heteropolymers with various monomer unites:3-hydroxybutyrate, 4-hydroxy- pentanoate, 3-hydroxydodecanoate, 3-hydroxy-tetradecanoate, 3-hydroxy-9-hexadecanoate, 3-hydroxyhe- xadecanoate, 3-hydroxy-11-octadecanoate, 3-hydroxy-9-octadecanoate, and 3-hydroxyocta- decanoate. A number of microorganisms in activated sludge in the process of waste water treatment were used for accumulating polyhydroxyalkanoates (PHA). Mixed bacteria and organic carbon source were used in microaerophilic-aerobic treatment of activated sludge and some cultural conditions: oxygen supply rate, attachment carbon The concentration of copolymers or heteropolymers with various monomer units: 3-hydroxybutyrate, 4-hydroxy-pentanoate, 3-hydroxydodecanoate, 3-hydroxy- tetradecanoate, 3-hydroxy-9-hexadecanoate 3-hydroxyhe-xadecanoate, 3-hydroxy-11-octadecanoate, 3-hydroxy-9-octadecanoate, and 3-hydroxyoctadecanoate.