The anticancer potential of anthraquinones danthron and quinizarin on highly metastatic B16-F10 melanoma murine cells was investigated. Several parameters related to cell proliferation and differentiation, i.e. cell number, intracellular content of polyamines, transglutaminase (EC 2.3.2.13) activity and melanin synthesis were evaluated. Tumor cell growth was strongly reduced after treatment with danthron and quinizarin, as well as polyamine intracellular levels. Moreover, the induction of differentiation in treated cells was demonstrated by the increase of transglutaminase activity. In vitro analysis of adhesion, wound healing migration and invasion showed a remarkable antimetastatic activity of the anthraquinones. The overall results suggest that danthron and quinizarin possess significant antineoplastic properties, probably exerted through the induction of intracellular transglutaminase activity.