The delivery of foreign DNA into eukaryotic cells is one of the most common molecular biology techniques to study biological mechanisms. However, unlike transformed cell lines, the efficient transfection of primary cells can be a problem. KeraFectagen is a cationic polymer-based transfection system specifically designed and optimized for efficient transfection of primary keratinocytes. Transfection with KeraFectagen can be carried out in the presence of antibiotics and serum. Instead of normal two-day transfection, an optimized one-day transfection procedure can be performed for time-saving and highly reproducible transfection. 1.25 ml of KeraFectagen reagent is sufficient for up to 250 transfections per well in 96-well plate.