Silk-fibroin (SF)-fiber-reinforced poly(epsilon-caprolactone) (PCL) biocomposites with different fiber contents were fabricated by a melt-blending method. The mechanical and viscoelastic properties of these SF/PCL composites were investigated by mechanical property testing, dynamic mechanical thermal analysis, and dynamic rheological analysis. The mechanical properties of PCL were obviously reinforced by fiber addition, and the maximum tensile and flexural strengths appeared at fiber contents of 35 and 45%, respectively. As the fiber content increased, both the storage modulus and loss modulus increased, whereas the glass-transition temperature of the PCL. component decreased. The appearance of a storage modulus plateau indicated the formation of reinforcement network structures in the SF/PCL composites, which enhanced the elasticity and viscosity of the composites. The interfacial interaction between the fiber and PCL matrix was not very strong. (C) 2008 Wiley Periodicals, Inc.