New 7-chloroquinolinyl thiourea derivatives derived from the corresponding 4,7-dichloroquinoline isothiocyanate were synthesized and evaluated for in vitro antimalarial and anticancer activity. The most active compound from the series displayed an inhibitory IC(50) value of 1.2 microM against the D10 strain of Plasmodium falciparum. Lack of cytotoxicity towards HeLa cells indicates selectivity towards parasites.