Membrane fouling due to the accumulation of natural organic matter, inorganic components and colloidal/particulate matter on the surface and/or in the pores of the membrane decreases the membrane permeability and therefore impedes the implementation and efficient performance of membranes in the production of drinking water regardless of influent water quality. The objective of this study was carried out to investigate the operating conditions of sand filteration (SF) influencing the permeability performance and fouling of membrane filtration (MF) processes. Applied filtration rates during this experiment were <120 m/d for the SF and 0.5 ㎥/㎡.d for MF. Influent concentration were on average turbidity <130 ntu and total organic carbon (TOC) <11 mg/L. As a result, both SF process and SF/MF system achieved the efficiencies of more than 90% in removing turbid matter, while the removal efficiency of TOC were 10-30% for SF process and 40-60% for SF/MF system. The SF/MF system achieved 2 times higher than that of SF process in removing TOC due to biofiltration by the bio-cake layer formed on the surface of media. For transmembrane pressure (TMP), TMP increasing rate of MF was in proportion to an increasing rate of turbid and organic matters. These results indicate that the introduction of the biofilm sand filter prior to MF process is necessary for membrane fouling mitigation.