Since treatment of landfill leachate is quite complicated, there is a need to develop a system that is capable of providing high treatment efficiencies. In this study, the treatment performance of a jet - loop membrane bioreactor (JLMB) operated at different organic loading rates was investigated by observing the changes in Chemical Oxygen Demand (COD), Total Kjehidahl Nitrogen (TKN) and Total Ammonia (NH3) concentrations. The same COD removal rates (83%) were observed at all the studied loading rates, and it should be noted that the biodegradable part of the leachate was removed completely. It was also observed that the NH4 - N / TKN ratios, which were found to be approximately 0.9, did not change throughout the study. However, further treatment technologies, such as reverse osmosis, nanofiltration or ion - exchange, should be employed for the complete removal of inert COD and NH3 in order to meet related discharge limits.