Niacinamide, an amide of vitamin B3 (niacin), is a hydrophilic endogenous substance. It is part of the pyridine nucleotides nicotinamide-adenine dinucleotide (NAD) and nicotinamide-adenine dinucleotide phosphate (NADP) in human skin. Its effects after epicutaneous application have long been described in the literature. Given a sufficient bioavailability, niacinamide has multiple positive effects on human skin depending on its concentration. Niacinamide is a well-tolerated and safe substance often used in cosmetics. Clinical data for its therapeutic use in various dermatoses can increasingly be found in the literature. Although the existing data are not sufficient for a scientifically founded evaluation, it can be stated that the use of niacinamide in galenic preparations for epicutaneous application offers most interesting prospects, especially on dry skin.