The advantages of membrane bioreactors (MBR) and integrated fixed-film activated sludge (IFAS) were combined in a novel process called here IFAS-MBR. In this study, the IFAS¬MBR process has been evaluated in a semi-real plant (4 m3/h), where plastic carriers for the support of The biology were introduced in the second aerobic chamber in an already existing MBR plant. The plant consista in two parallel unes, one working with a hollow fiber module and the other with a fíat sheet module. After the IFAS-MBR, an RO system treats the effluent. The permeability of the process decreased gradually along the experimentation period and after six months, the membranes of both lineo of the IFAS-MBR had to be chemically cleaned. The RO membranes showed a good permeability working with the IFAS-MBR permeate and needed chemical clearing after four months of operation. The process appears as an interesting process when the footprint is limited or a high effluent quality is required, and the resulto show it as an attractive pretreatment for reverse osmosis systems.