The skin, as an interface between the organism and the external environment, plays a major role in protecting and supporting the life it encloses. Elias proposed the 'brick and mortar model', in which the SC is composed of flat cells of corneocytes with cornified envelope and cytoskeletal elements, as well as corneodesmosomes (bricks) surrounded by lipid-enriched intercellular domains matrix (mortar). Since then, many studies have been performed to elucidate the role of the SC at the organismal, biochemical and molecular biological levels. During epidermal differentiation, lipids are synthesized in the keratinocytes and extruded into the extracellular domains, where they form extracellular lipid-enriched layers. Meanwhile, Human epidermis displays a characteristic calcium gradient, with lower calcium levels in the basal and spinous layers, which increases progressively towards the outer SG. The Ca2+ gradient has been shown to regulate lamellar body secretion independent of barrier formation. In this session, we discuss the basic concept of epidermal barrier and application of laser and/or energy-based devices (EBD) to impaired epidermal permeability barrier as well as, alteration of epidermal permeability barrier after laser and/or EBD therapy on the skin.