Antimicrobial peptides (AMPs) are extremely attractive candidate for therapeutic agents due to their wide spectrum of antimicrobial activity and action mechanism different from antibiotics. In this study, a method using genetic engineering for obtaining an antimicrobial peptide, bovine lactoferricin derivative peptide LfcinB-W10, has been developed. According to the coden usage of Escherichia coli, a gene encoding the peptide was synthesized and a recombinant vector of E. coli expression pGEX-EN-LFW was constructed. The LfcinB-W10 peptide fused with glutathione S-transferase (GST) was successfully expressed and about 20 mg fusion protein with 90% purity was obtained from 1 l culture. The recombinant LfcinB-W10 (rLfcinB-W10) was released from fusion protein by the enterokinase digestion, and about the LfcinB-W10 yield reached 300 mu g per 1 l culture. The purified rLfcinB-W10 was found to have growth inhibition activity against Staphylococcus aureus (S. aureus) ATCC25923.