The anaerobic ammonium oxidation (anammox) activity was evaluated using sludge obtained from the rhizome of Typha sp., found in a natural wetland localized in the J´ose Antonio ´ Alzate dam, Toluca Valley,Mexico. Five NO2 -N concentrations (15, 30, 50, 70 and 100 mg/L) were evaluated and the ammonium remained constant at 100 10 mg N/L. All cultures presented a lag phase in the ammonium consumption. Nevertheless, after the phase lag the ammonium oxidation was linked to nitrite reduction, producing N2. The nitrite consumption eciencies for the concentrations evaluated from 15 to 50 mg/L of NO2 -N were above 95%, while the ammonium consumption eciency increased from 14 to 48%. In experiments with 70 and 100 mg/L of NO2 -N, nitrite consumption eciencies were 74 and 58% respectively. The higher nitrite concentrations tested inhibited the anammox process since the specific rates diminished at 0.51 and 0.44 mg NO2-N/g VSS d respectively. This study provides new and useful information about the anammox activity in sludges coming from wetlands, and these can be used as potential inoculum to treat wastewaters into anammox reactors, or in constructed wetlands.