A novel halophilic strain that could carry out heterotrophic nitrification and aerobic denitrification was isolated and named as Halomonas campisalis ha3. It removed inorganic nitrogen compounds (e.g. NO3 (-), NO2 (-) and NH4 (+)) simultaneously, and grew well in the medium containing up to 20 % (w/v) NaCl. PCR revealed four genes in the genome of ha3 related to aerobic denitrification: napA, nirS, norB and nosZ. The optimal conditions for aerobic denitrification were pH 9.0, at 37 A degrees C, with 4 % (w/v) NaCl and sodium succinate as carbon source. The nitrogen removal rate was 87.5 mg NO3 (-)-N l(-1) h(-1). Therefore, this strain is a potential aerobic denitrifier for the treatment of saline wastewater.