The features of a system of a fatty acid/lecithin (lipid combination) lamellar liquid crystal combined with the liquid crystal formed from Polysorbate 80 (Tween 80, polyoxyethylene 20 sorbitan oleate, commercial quality) and water were examined by X-ray diffraction and microscopy. For a low ratio of Polysorbate 80 to lipid combinations a simple lamellar structure was formed as was the case for high water content. At low water content and high ratio of Polysorbate 80 to lipid combinations two lamellar structures were indicated by the X-ray results. The change from a single lamellar structure to two structures was reversible with change in temperature or water content. The reason for the coexistence of the lamellar structures was ascribed to difference in head group size.