Several poly(lactic acid) (PLA)-polyethylene glycol (PEG)-PLA triblock copolymers with PLA segments of different molecular weights were synthesized by ring-opening anion polymerization and used as hydrophilic additives for PLA hollow fiber membranes. PLA hollow fiber membranes were prepared via the non-solvent induced phase separation method. The effects of PLA-PEG-PLA copolymer addition on the membrane morphology and characteristics were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy, elemental analysis, and water contact angle measurements. The residual ratio of the PLA-PEG-PLA copolymer with the largest PLA molecular weight was almost 100%, while it was only about 10% for PEG. Addition of the PLA-PEG-PLA copolymer, which showed a high residual ratio in the membrane, effectively improved the hydrophilicity of the PLA hollow fiber membrane. Fouling experiments using bovine serum albumin and humic acid solutions revealed that the anti-fouling properties of the PLA hollow fiber membranes were remarkably improved by blending with the PLA-PEG-PLA copolymers. (c) 2012 Elsevier B.V. All rights reserved.