Ultrafiltration (UF) membranes with high permeability and good fouling resistance hold great promise in water treatment and many industry sectors. Herein, antifouling UF composite membranes with mesoporous films of polystyrene (PS)/poly(ethylene oxide) (PEO) block copolymer as the selective layers were produced by the process of selective-swelling-induced pore generation. We spin-coated thin layers of block copolymer onto macroporous supports, and activated the copolymer layers by soaking them in hot ethanol to induce the selective swelling of the PEO microdomains. The porous structures of the block copolymer selective layers can be continuously modulated simply by varying the swelling durations, resulting in UF membranes with water permeabilities adjustable in the range of similar to 100 to 600 L m(-2) h(-1) bar(-1). Interestingly, the hydrophilic PEO blocks were enriched on the pore walls after swelling, rendering an inherent fouling resistance to the membranes. Protein fouling tests demonstrated that the membrane exhibited exceptional fouling resistance with a recover ratio in water flux of nearly 100%. This fouling resistance is expected to be long-standing as the PEO chains are covalently bonded to the membrane matrix.