The EpiSkin(commercialised by SkinEthic) has been validated byECVAM (European Centre for the Validation of AlternativeMethods) as an irritation potential. Charles River performs EpiSkin® reconstructed human epidermis modelin vitro alternative for the assessment of skin® in vitroirritation studies in accordance with the ECVAM validationSOP. The skin units have a limited and defined period ofviability from the day of production and the SOP states thatthey should be pre-incubated for at least 24 h prior to dosing.Delays in delivery of the Episkinin the 24 h pre-incubation being impractical. This study wasdesigned to assess the effect of a shortened, 2 h,pre-incubation on the performance of the assay.® units can, therefore, result