A series of biodegradable block copolymers consisting of poly(γ-benzyl L-glutamate) (PBLG) and poly(ethylene oxide) (PEO)-lactoselactone were prepared by polymerization of PEO-lactoselactone and γ-benzyl L-glutamate-N-carboxyanhydride and characterized by IR and NMR. From circular dichroism measurements, it was found that the polymers exist in the α-helical conformation. Block copolymer microspheres were prepared by solvent-extraction-precipitation method for their primary evaluation for medical and biological applications.