The aim of this study was to investigate efficiency of ammonium nitrogen removal from municipal landfill leachate in activated sludge in two-stage SBR reactors. Treated leachate contains low concentrations of organic substances measured as chemical oxygen demand (COD) - 757 mg O₂/dm³ and high concentrations of ammonium - 362 mgN_NH4/dm³. Nitrification was studied in two parallel, aerated SBR reactors with two different hydraulic retention times (HRT), 3 and 2 days, respectively. We have found that 2 days HRT was sufficient to achieve complete nitrification. In the effluent ammonium, nitrite and nitrate nitrogen concentrations were 0.08 mgN _NH4/dm³, 0.04 mgN _NO2/dm³ and 320 mgN _NO3 /dm³, respectively. The ammonium nitrogen removal rate was 20.2 mgN _NH4 /dm³.h. The effluent from aerobic reactors (HRT 2 days) was fed to the anoxic SBR reactors. An external carbon source (methanol) was added to promote denitrification. In the anoxic reactor, at a methanol dosage 3.6 mg COD/mg N _NO3 and HRT of 1 day complete denitrification was achieve with nitrate nitrogen residual concentrations of 0.9 mgN_NO3/dm³. The maximum denitrification rate was 48.4 mgN _NOx/dm³.h. The highest values of the yield methanol coefficient Y _m/N-NOx were determined for dosages 3.6 mg COD/mg N_NO3 and 5.4 mg COD/mg N_NO3, the lowest for 1.8 mg COD/mg N_NO3.