One of key functions of the epidermis is to form a barrier between the organism and the ouside world. The permeability barrier of the skin is localized in the stratum corneum and consists of protein enriched corneocytes and lipid-enriched intercellular domains. In injured or diseased skin, the skin barrier function is usually disturbed and percutaneous absorption of chemicals and drugs is increased. Percutaneous absorption is also increased through chemical means by the use of penetration enhancer, through physical means as phonphoroesis and iontophoresis and by the use of liposomes.