Abstract: A composition which when topically applied to the skin of a mammal reduces trans-epidermal water-loss and provides an improved epidermal barrier contains an aqueous dispersion of at least two lipids, preferably at least three lipids, in a non-crystalline phase lamellar array, preferably bilayer membranes in the form of liposomes. These lipids adopt a crystalline lamellar phase upon application to mammalian skin which resist washing with mild detergents and water. The composition can be formulated as a pharmaceutical preparation, and can be used in a method of recovering or otherwise improving a mammalian skin permeability barrier by administering the composition to the skin or hair and allowing the composition to dry. The dried composition adopts a crystalline lamellar phase after said administering to the skin. The composition thus provides a permeability barrier in cases where the natural barrier has been depleted, damaged or requires improvement.