Interaction of lactoferrin and its peptides LfcinB4-14 and LfampinB with dipalmitoylglycero-phosphocholine (DPPC) and dipalmitoylglycero-phosphoglycerol (DPPG) liposomes were studied by means of Raman spectroscopy. In our study, conformational changes in the phospholipid molecules were investigated by measuring the intensities of 2 847 and 2 882 cm(-1) Raman bands which are assigned to acyl chains' symmetric and asymmetric C-H stretching vibrations. The addition of lactoferrin and its peptides LfcinB4-14 and LfampinB caused a decrease in the 2 882 cm(-1) intensity of DPPG liposomes, thus the order parameter for the lateral interactions between chains S(lat) decreased from 0.19 to 0.17, 0.14 and 0.12 respectively. On the contrary, the intensities at 2 847 and 2 882 cm(-1) of DPPC liposomes were poorly affected by lactoferrin and its peptides. The results show that lactoferrin and its peptides present a stronger effect on the molecular structure and order degree of anionic lipid DPPG than that of zwitterionic lipid DPPC. This suggests that lactoferrin, LfcinB4-14 and LfampinB can interact and combine with the negatively charged DPPG liposomes by electrostatic interaction and perform its antibacterial activity. Besides, LfcinB4-14 and LfampinB can affect the lipid more strongly than lactoferrin.