Despite their widespread use and potential for significant human exposure, genotoxicity data on anthraquinones and other dyes are generally limited. The study examined 16 anthraquinones and one azo dye (Solvent Red 1) using the thymidine kinase (tk) locus and micronucleus (MN) analysis in L5178Y/TK(sup +/-) -3.7.2C mouse lymphoma cells. Disperse Blue 7, 2-aminoanthraquinone, 1-amino-2-methylanthraquinone, Disperse Blue 3, and Disperse Red 11 were genotoxic. Reactive Blue 19 was weakly mutagenic. Vat Yellow 4 and Solvent Red 1, with exogenous activation, were also mutagenic. With activation 1-nitro-2-methylanthraquinone was judged to give an equivocal mutagenicity response. Those chemicals that did not induce mutation or cytotoxicity at the limits of solubility were classified separately. Compounds which were not evaluated without exogenous activation because of insolubility but were evaluated with activation include 1-nitro-2-methylanthraquinone, Solvent Red 1, and Vat Yellow 4. Compounds which were not evaluated either with or without S-9 activation because of their insolubility in the culture medium include 1-amino-2,4-dibromoanthraquinone, D&C Green, Disperse Blue 1, Disperse Red 60, Vat Blue 4, Vat Blue 20, Vat Brown 1, and Vat Brown 3.