Poly(lactic acid) (PLA) is attracting a lot of attention as a bio-based polymer derived from plant resources. A hollow fiber membrane made from PLA is an alternative to the conventional hollow fiber membrane of petrochemical polymers. In this study, we succeeded in the preparation of a PLA hollow fiber membrane using phase separation method. PLA hollow fiber membranes with various structures were prepared by varying the preparation conditions (bore fluid composition and additive). The water permeability of the hollow fiber membrane increased as the DMSO content in the bore fluid and the PEG content in the PLA solution increased. The investigation of protein (BSA) rejection revealed that PLA hollow fiber membranes exhibited ultrafiltration performance. We found that controlling the experimental conditions allowed two different types of phase separation (liquid-liquid phase separation and solid-liquid phase separation) in the preparation of a PLA hollow fiber membrane, resulting in the variety of the microporcrus structures of the hollow fiber membrane. (C) 2009 Elsevier B.V. All rights reserved.