Parasitic infections such as leishmaniasis, trypanosomiasis and malaria have significant impacts in third world countries and are the major reasons of mortality. In order to search a new class of antiprotozoal agent, a series of ten quinolin-2-one derivatives was tested in vitro against the parasites causative of malaria, leishmaniasis, sleeping sickness and Chagas´ disease. In general, these compounds exhibited moderate activity against Plasmodium falciparum and showed no activity against Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei. Facing to establish a possible mechanism of antimalarial activity their binding to hemin was assayed. Furthermore, the need of developing new therapeutic strategies for the effective control of tuberculosis prompted us to assay twelve of these compounds against Mycobacterium tuberculosis but they did not demonstrate inhibitory activity. In addition, three terms resulted also structurally related to linomide, a recognized drug against angiogenesis, an interesting target for designing new antineoplastic agents. So these compounds were selected at the National Cancer Institute for angiogenesis testing and they exhibited similar activity to those recently reported for linomide and its analogues