An original method is proposed for the purpose of discriminating between antimetabolites exhibiting different operating mechanisms. The present work was carried out by means of the digital cell image analysis of Feulgen-stained nuclei cultured in the presence of different antimetabolites. We chose this method because it enables anticancer drug-induced effects to be studied at both morphonuclear and cell cycle levels in the same biological sample. The results show that all the antimetabolites had similar effects on the nuclear texture of the cells and on cell cycle parameters. Furthermore, the use of multivariate analyses made it possible to distinguish between different mechanisms of action among drugs belonging to the same class of antineoplastic, i.e. antimetabolite agents.