Low-fouling ultrafiltration (UF) membranes have been prepd. by simultaneous photograft copolymn. of poly(ethylene glycol) methacrylate (PEGMA) onto a polyethersulfone (PES) membrane with a nominal cut-off of 50 kg/mol. A comprehensive characterization was performed by flux measurement and sieving curve anal., FTIR-ATR spectroscopy, contact angle and zeta potential measurement. The effects of UV irradn. and monomer concn. on membrane characteristics as well as membrane performance were also described. Model solns. of sugarcane juice polysaccharides and the protein BSA were used to examine the membrane performance. The results showed that UV irradn. time was the most important parameter with monomer concn. as another parameter to adjust the degree of functionalization. All modified membranes showed more resistance to fouling and higher rejection than unmodified membrane for both model solns. A redn. of permeability due to pore constriction or even blocking by grafted PEGMA was also obsd. Surface functionalization of PES UF membranes using relatively high monomer concn. (40 g/L) at medium irradn. times (1.5-3 min) was recommended as the best condition with respect to flux, rejection and fouling. This study provides valuable information for the development of low-fouling ultrafiltration membranes esp. for sugarcane juice clarification.