Forty bis(9-amino-6-chloro-2-methoxyacridines), in which acridine moieties are joined by alkanediamines, polyamines, or polyamines substituted by a side chain, were synthesized and tested for their in vitro activity upon the erythrocytic stage of Plasmodium falciparum, trypomastigote stage of Trypanosoma brucei, and amastigote stage of Trypanosoma cruzi and Leishmania infantum as well as for their cytotoxic effects upon MRC-5 cells. Results clearly showed the importance of the nature of the linker and of its side chain for antiparasitic activity, cytotoxicity, and cellular localization. Among several compounds devoid of cytotoxic effects at 25 microM upon MRC-5 cells, one displayed IC(50) values ranging from 8 to 18 nM against different P. falciparum strains while three others totally inhibited T. brucei at 1.56 microM.