The inhibitory effect of high-strength NH3-N on anaerobic biodegradation of landfill leachates in an EGSB bioreactor has been investigated. The research compared start-up performance of the reactor treating the landfill leachate with NH3-N in 242-1200 mg/l to that treating the compost leachate with NH3-N in 38-410 mg/l. The observations showed that the performance of the reactor treating the landfill leachate was only marginally worse than that treating the compost leachate at the mesophilic temperature when NH3-N concentration was under 1500 mg/l. We also noted that NH3-N at the concentration of 1500-3000 mg/l inhibited the biodegradation. The comparative biodegradation performance at the mesophilic and atmospheric temperature demonstrated that the maximal OLR of atmospheric digestion was only reduced to 44 kg COD/m(3) d. These findings indicate that landfill leachates with NH3-N less than 1500 mg/l could be efficiently treated in the EGSB bioreactor even under the atmospheric condition with methane generated. (C) 2011 Published by Elsevier Ltd.