The binding of myoglobin to liposome was studied by using the ultracentrifugation method. It was found that the binding was maximum in the acidic pH region and the incorporation appears to be mainly through hydrophobic interactions. The proteolysis of protein-vesicle complex with trypsin followed by the determination of amino acid composition of the segment suggested that the N-terminal region goes into the bilayer. The binding behavior of myoglobin to vesicles and its structure in the acidic pH range is related closely.