Six environmentally relevant polycyclic aromatic hydrocarbons were tested in dose-response experiments of topical application to mouse skin with regard to local carcinogenicity: benzo(a)pyrene (BaP), benzo(b)- (BbF), benzo(j)- (BjF), and benzo(k)-fluoranthene (BkF), indeno(1,2,3,-cd) pyrene (IP), cyclopentadieno(cd)pyrene (CP), and coronene (COR). Of these compounds, BaP and BbF proved to be carcinogenic, BjF and CP were weakly carcinogenic whereas BkF, IP and COR showed no cancer-inducing effects. In the dose range investigated BbF has about 1/3 and CP about 1/20 of the activity of BaP.