Qinghao is a Chinese traditional herb.The effectiveness of its compound Qinghaosu against malaria is well estab- lished.Qinghao and its extracts were tested in vitro for antiparasitic activity against four aerobic parasites Toxo- plasma gondii,Leishmana donovani,Trypanosoma gambicnsia,and Trypanosoma cruzi,and three anerobic parasitcs Entamobca histolytica,Trichamonas vaginalis, and Giardia lamblia.This results show that Qinghao methanal extract and Qinghaosu completely eliminated T.gondii in fibroblasts,and prartly inhibited the growth of L.donovani and T.gambiensia.Qinghao water ex- tract and Qinghaosu also partly inhibited the growth of T.cruzi,of the 2 Qinghaosu derivatives tested, artemether was the move effective than that of Qinghao- su and dihydroqinghaosu.The datd suggests Qinghao and its extracts may be effective on against aerobic plas- modium.