This paper summarises the results obtained on a laboratory scale under development and optimisation of a new nitrogen removal process called DEAMOX (DEnitrifying AMmonium OXidation) for treatment of strong nitrogenous wastewater. The concept of this process combines the recently discovered anammox (anaerobic ammonium, oxidation) reaction with denitrifying conditions for generation of nitrite from nitrate. Both the autotrophic (sulphide-driven) and heterotrophic (organics-driven) modifications of the DEAMOX process are reviewed with regard to process performance as well as outcome of competition for nitrite between anammox and denitritation. Some microbiological characteristics of the unique DEAMOX sludges formed during long-term runs are also discussed.