In healthy skin the stratum corneum has typically a water content of 20% and provides a relative effective barrier against percutaneous absorption of exogenous substances. Skin occlusion can increase the stratum corneum hydration and therefore influence percutanious absorption. For cosmetic products it is important that the cosmetic active is not systemically absorbed. But a certain penetration into the skin is needed to obtain a cosmetic effect. In general lipid nanoparticles do not penetrate the horny layer but a follicular uptake by the hair follicles has been reported for particulate system. Improved dermal uptake of active compounds loaded to lipid nanoparticles might also result from an increased contact surface of the active compound with the corneocytes, a rapid or a steady release and surfactants