Dermatological reports in accordance with scientific criteria are of decisive value for the safety and efficacy of cosmetics. The latest alterations in European legislation emphasise this fact. Whether a cosmetic product is well tolerated or causes irritations or allergic reactions must be proven by dermatological tests. The following effects of skin care products can be studied in a quantitative way: protection against sun radiation, moisturisation/hydration of the skin, reduction of skin roughness, reflection of light from the skin surface, water loss changes with the function of cosmetic treatments, effects of cosmetic products on skin temperature, skin pH, skin topography, e.g. skin roughness, skin friction, analysis of cell layers of the stratum corneum and the stratum spinosum. The value of dermatological reports directly depends on the respectability of the commissioned dermatologists. Pitfalls occur whenever non qualified scientific results are generously used for advertising campaigns such as ‘dermatologically tested’, ‘allergy tested’, ‘hypo-allergen’ etc. Additionally many reports are scientifically insufficient. Dermatological reports on cosmetics therefore must be valid in scientific methods and practical execution. We report on more than 35 years of practical testing.