The MBR technology has evolved rapidly over the past two decades with significant gains in performance andreliability, and reductions in costs. Membrane bioreactors (MBR) technology is widely recognised as offering a key optionfor enhanced wastewater treatment or reuse. The objective of this paper is then to critically review the remarkable achievementon the research and commercial applications of membrane bioreactor (MBR) technology and to present current andpotential MBR markets on a global scope. This brief review of the technology incorporates five key aspects : 1) evolutionof MBR practice, 2) the commercial technologies of MBRs, 3) the largest MBR installations globally (e.g. > 10,000 m³/day),4) MBR market growth, and 5) directions for future research. Finally, the development directions of economical, environmentaland technical aspects in MBRs; 1) investment costs; 2) effluent water quality; 3) membrane materials and modules;4) MBR equipment and treatment process; 5) operating costs (higher energy & chemical consumption); and 6) sustainabilitysuch as anaerobic MBRs in the coming years were addressed.