A number of studies have reported the anti-tumoral activity of lactoferrin, a property mediated by a variety of mechanisms such as inhibitory effects on tumor cell growth, NK cell activation, and enhancement of apoptosis. Liposomes are known to be an efficient drug delivery system which can enhance the therapeutic potential of the encapsulated compounds. We have used positively charged liposomes composed of phosphatidylcholine (PC), dioleoylphosphatidylethanolamine (DOPE), cholesterol (Chol) and stearylamine (SA) (6:1:2:1 M ratio) as a carrier system for bovine iron-free Lf (ApoBLf), and compared the in vitro effect of free and liposome-entrapped ApoBLf on the growth and morphology of murine melanoma B16-F10 cells. Liposomal formulation of ApoBLf was found to enhance the capacity of the protein to inhibit the cell proliferation by affecting cell cycle progression. The effect appeared to be due to the capacity of liposomes to increase the uptake of the protein and its accumulation into cells and probably to protect it from degradation, as revealed by fluorescence microscopy and flow cytometry. Our results demonstrate the ability of liposomes to improve the anti-tumor activity of Lf and suggest that liposomal protein may have a potential therapeutic use in the prevention and/or treatment of cancer diseases.