Nitrogen removal has been observed during soil aquifer treatment (SAT) at many sites where nitrogen is primarily added to the soil as ammonia-nitrogen. A common hypothesis for this nitrogen removal in SAT is the two-step process of autotrophic nitrification and heterotrophic denitrification. However, few SAT systems have the biological oxygen demand (BOD) to nitrogen (N) ratios that can sustain heterotrophic denitrification. Most system conditions would result in maximum heterotrophic nitrogen removal efficiencies of about 30%, whereas, much higher nitrogen removal efficiencies have been observed in SAT systems. This would suggest that some other mechanisms are responsible for the additional nitrogen removal. Therefore, a proposed sustainable mechanism for denitrification in SAT systems is anaerobic ammonium oxidation (Anammox). This paper reports the results of batch tests used to assess the presence of anaerobic ammonium oxidation in an SAT soil. These batch experiments compared the gas production and ammonia and nitrate removal rates of the Anammox tests to heterotrophic denitrification tests and blanks. The gas production results demonstrated that autotrophic denitrification occurred in the Anammox test set. Typical heterotrophic denitrification would result in the production of CO2 and N2 gases. The observed N2 gas production in the Anammox test set did not correlate with the CO2 gas production. This suggests that some other mechanism is responsible for the denitrification observed. This preliminary experiment has identified the presence of microbes and provides a basic testing method that can be employed in future studies of the Anammox process during SAT. Includes 16 references, tables, figures.