The efficiency of organics and nitrogen removal from municipal landfill leachate in activated sludge operated as single and two-stage SBR were investigated. Leachate from mature landfills are characterized by high N/COD ratio (> 0.5). In single activated sludge system at the hydraulic retention time (HRT) 3d and at methanol dosage 8 mg COD/mg N_NO3 complete ammonium nitrogen removal was obtained. Ammonium concentration in the effluent was 0.15 mg N_NH4/dm³ and nitrate - 23.5 mg N_NO3/dm³ . At the hydraulic retention time 2d, nitrate nitrogen concentration in the effluent decreased to 2.79 mg N_NO3/dm³. The concentration of ammonium nitrogen was 0.35 mg N_NH4/dm³. However, a sporadically high concentration of ammonium appears. In a two-stage SBR system, HRT 2d was sufficient to achieve complete nitrification. In the effluent ammonium and nitrate concentrations were 0.08 mgN_NH4/dm³ and 320 mgN_NO3/dm³, respectively. In the anoxic reactor at HRT 1d and methanol dosage 3.6 mg COD/mg N_NO3 complete denitrification was obtained. Raw leachate contained specific hazardous organics, among others BTEX (175.8 µg/dm³), chloroorganics (55.7 µg/dm³), chlorobenzenes (0.75 µg/dm³) and PAHs (1.97 µg/dm³). In the effluent from single and two-stage SBR systems chloroorganics and chlorobenzenes were not detected. BTEX and PAH concentrations in the effluent from two-stage system were adequately 2-fold and 2.1-fold lower in comparison to a single one. Besides, the effluent from two-stage SBR systems did not contain benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene and indeno(1,2,3-cd)pyrene.