Moxipraquine is alkylaminopiperazinyl derivative patented by Wellcome Foundation Ltd. as antiparasitic agent effective against Trypanosoma cruzi. Moxipraquine was effective in suppressing parasitaemia but did not eradicate the infection from mice or guinea-pigs. Moxipraquine was less potent against mouse infections with strain Peru than it was against other strains of T. cruzi. In limited tests, moxipraquine was effective on experimental infections of Leishmania major, L. mexicana mexicana and L. brasiliensis panamensis but not L.b. brasiliensis. Significant foetal toxicity, observed experimentally in rats and rabbits, resulted in the termination of further trials.