In this article, core-shell structure nanofibers were fabricated by coaxial electrospinning with biodegradable copolymer Poly(-Lactic-epsilon-Caprolactone) [P(LLA-CL) 50 : 50] as shell and bovine serum albumin (BSA) as core. Morphology and microstructure of the nanofibers were characterized by scanning electron microscopy and transmission electron microscopy. The mechanical properties were investigated by stress-strain tests. In vitro degradation rates of the nanofibrous membranes were determined by measuring their weight loss when immersed in phosphate-buffered saline (pH 7.4) for a maximum of 14 days. Release behavior of BSA was measured by an ultraviolet-visible spectroscopy, and the results demonstrated that BSA could release from P(LLA-CL) nanofibers in a steady manner. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 1564-1570, 2009