The in vitro antimalarial activity against human malaria parasite (Plasmodium falciparum, FCR-3 strain) was examined using 59 triterpenoids obtained during studies on teh triterpenic constituents of Cimicifuga spp. The 50% effective concentration values (EC₅₀) of 25 active triterpenoids were 1.0-3.0 μM, and 19 of the compounds had a common 16, 23 : 23, 26 : 24, 25-triepoxy group in the side-chain moieties. Among the active triterpenoids. 9 also showed significant inhibition of nucleoside transport in mouse spleocytes A relationship between the antimalarial, activity and the inhibition of nucleoside transport involving these triterpenoids is discussed.