Acridines belong to a group of polycyclic heteroaromatic compounds and exhibit a broad spectrum of biological activity including antiprotozoal, antibacterial, antiviral and antitumor activity. Acridine derivatives with antitumor activity have different mechanisms of action at the molecular level. The data obtained so far indicate that one of the main steps is the formation of physico-chemical complexes with DNA. Among acridine derivatives with anticancer activity we can distinguish five main classes of compounds: nitroacridines, 9-anilinoacridines, pyrazoloacridines, imidazoacridines, and triazoloacridines. Compounds from different classes differ both in mechanism of action and spectrum of antitumor activity.