In the previous work, methanol extracts of Carpesium rosulatum (Compositae) were found to have high antiplasmodial activity against Plasmodium falciparum in vitro, this activity being largely attributable to a ineupatorolides A (I-A). In the present study, encouragingly, I-A was also found to have potential antimalarial activity in vivo when tested against Plasmodium berghei in mice. I-A (2, 5, 10 mg kg(-1) day(-1)) exhibited a significant blood schizontocidal activity in 4-day early infection, repository evaluation, and in established infection with a significant mean survival time comparable to that of the standard drug, chloroquine (5 mg kg(-1) day(-1)). The I-A possesses a promising antiplasmodial activity, which can be exploited in malaria therapy.