Using four Salmonella typhimurium tester strains (TA1537, TA1538, TA98 and TA100) and the promutagen 2-aminoanthracene, an epidermal S9-mediated mutagenicity assay was developed. Using an activation mixture derived from whole skin of the rat, mutagenicity was observed in tester strain TA98 whereas an activation mixture derived from the dermis resulted in mutagenicity in tester strains TA1538, TA98 and TA100. Activation mixtures from both the epidermis and the liver produced a positive response in all of the tester strains studied. Activation mixtures from liver were shown to have the highest specific activity followed in decreasing order of potency by epidermis, dermis and whole skin. These results indicate that the skin, a target tissue directly exposed to environmental chemicals, is capable of converting 2-aminoanthracene to mutagenic moieties. Since the skin of the rat is known to be susceptible to tumor induction by 2-aminoanthracene our findings re-emphasize that membrane-bound enzymes can influence toxic responses including mutagenicity to xenobiotics in cutaneous tissue.