Computer-implemented method for predicting the permeability of a stratum corneum lipid matrix to a compound, comprising the steps of: a) providing a model of the stratum corneum lipid matrix representing at least one repeating unit and comprising ceramides, free fatty acids, cholesterol and water, which model comprises the following: i) 30-35 % total ceramides based on the molar concentration of all components except water, of which more than 90 % are in extended configuration; ii) 30-35 % free fatty acid, based on the molar concentration of all components except water, wherein less than 10 % of the free fatty acids are negatively charged; iii) 30-35 % cholesterol, based on the molar concentration of all components except water, wherein 20-30 % of said cholesterol is located by the fatty acid moiety of said ceramides and 80-70 % of said cholesterol is located by the sphingoid moiety of the ceramides and wherein less than 10 % of the cholesterol molecules are replaced by cholesterol sulfate molecules; and iv) 0.2-2 water molecules per ceramide molecule; wherein said model of the stratum corneum lipid matrix comprises approximately 1-8 % O-acyl ceramides, based on the molar concentration of all components except water; b) providing the molecular designators of a compound to which the permeability of the stratum corneum lipid matrix is to be predicted, and c) calculating, via means of computer simulation, the predicted permeability of the stratum corneum lipid matrix to said compound using said model and the molecular designators of the compound. a) providing a model of the stratum corneum lipid matrix representing at least one repeating unit and comprising ceramides, free fatty acids, cholesterol and water, which model comprises the following: i) 30-35 % total ceramides based on the molar concentration of all components except water, of which more than 90 % are in extended configuration; ii) 30-35 % free fatty acid, based on the molar concentration of all components except water, wherein less than 10 % of the free fatty acids are negatively charged; iii) 30-35 % cholesterol, based on the molar concentration of all components except water, wherein 20-30 % of said cholesterol is located by the fatty acid moiety of said ceramides and 80-70 % of said cholesterol is located by the sphingoid moiety of the ceramides and wherein less than 10 % of the cholesterol molecules are replaced by cholesterol sulfate molecules; and iv) 0.2-2 water molecules per ceramide molecule; wherein said model of the stratum corneum lipid matrix comprises approximately 1-8 % O-acyl ceramides, based on the molar concentration of all components except water; i) 30-35 % total ceramides based on the molar concentration of all components except water, of which more than 90 % are in extended configuration; ii) 30-35 % free fatty acid, based on the molar concentration of all components except water, wherein less than 10 % of the free fatty acids are negatively charged; iii) 30-35 % cholesterol, based on the molar concentration of all components except water, wherein 20-30 % of said cholesterol is located by the fatty acid moiety of said ceramides and 80-70 % of said cholesterol is located by the sphingoid moiety of the ceramides and wherein less than 10 % of the cholesterol molecules are replaced by cholesterol sulfate molecules; and iv) 0.2-2 water molecules per ceramide molecule; b) providing the molecular designators of a compound to which the permeability of the stratum corneum lipid matrix is to be predicted, and c) calculating, via means of computer simulation, the predicted permeability of the stratum corneum lipid matrix to said compound using said model and the molecular designators of the compound. <EOS>