The kinetics of penetration and metabolism of BaP, BACs, DB(a,h)ACs and DB(c,g)Cs in the skin of hairless mice was studied. The relative fluorescence intensities were measured during three hours after applying 10 nmoles of the compound to the interscapular region of the mice. By using a kinetical model which combines a non-steady diffusion of a hydrocarbon through the stratum corneum and the metabolic oxidation by epidermal cells, the rate constants for the two processes were calculated. It has been shown that B(a)AC, B(c)AC and 12-MB(a)AC penetrate into the skin and are oxidized by epidermal cells more efficiently than BaP. In contrast, alkyl-DB(a,h)ACs (except 14-MDB(a,h)AC) show a great stability in the mouse skin. The carcinogenic BaP, 7-MB(c)AC and DB(a,h)AC have average rates of elimination from the skin.