Random coil silk fibroin membrane was designed to dissolve with HFIP, and regenerated silk fibroin fibers were obtained by wet spinning. The effect of coagulants (methanol and ethanol) on structure, mechanical properties, and actinomyces biodegradability of regenerated silk fibroin fiber was investigated through X-ray diffraction, IR spectra, and TGA. The results showed that the effect on the structure and properties of regenerated silk fibroin fibers coagulated by methanol and ethanol was negligible, but the difference in actinomyces biodegradability in vitro was obvious. (c) 2007 Wiley Periodicals, Inc.