Hydration of skin is significantly influenced by the content and proportion of epidermal fats produced mainly by keratinocytes. Some fats forming the hydrolipid skin surface film are also produced by the sebaceous glands. This film makes the skin supple and elastic and represents the important barrier against bacteria and moulds. Lot of methods for skin hydration mesasurement has been developed to study the skin physiology and pathology and follow the healing effect of topical drugs and cosmetics and their influence on the skin hydration. Article summarizes direct methods based on the capacity, impedance and conducti-vity measurement. Indirectly the hydration could be assessed also by elasticity measurement, TEWL, colorimetry, spectrophotometry, profilometry and magnetic resonance. The use of commonly available devices, concerned to be the standard of this measument, Corneometer, Nova Dermal Phase Meter and Dermalab (3 types of probes) is mainly discussed. Some examples are demonstrated. In future studies we want to objectify the hydration condition using the above mentioned methods, if and how it was influenced by some of the proposed therapeutic methods and procedures

        Key words: epidermal fats - pilosebaceous unit - natural moisturing factors - hydration measument -hydrolipid film - hydration measuring devices