Ajuga remota Benth is the most frequently used plant to treat malaria by Kenyan herbalists. Both crude extracts and pure isolates of the plant were tested for their in vitro antimalarial properties. The activity was assessed by an enzyme assay method based on the measurement of the parasite lactate dehydrogenase activity. The IC50 of the most active A. remota extract (ethanol macerate) was 71 and 69 μg/ml against the chloroquine sensitive (FCA/20GHA) and resistant (W2) strains of Plasmodium falciparum respectively. Ajugarin-1 was moderately active with IC50 of 23.0 ± 3.0 μM as compared to chloroquine (IC50 = 0.041 ± 0.003 μM) against the chloroquine-sensitive strain of Plasmodium falciparum. Ergosterol-5, 8-endoperoxide was about 4x as potent (IC50 = 5.4 ± 1.9 μM) while 8-0- acetylharpagide, a new isolate of A.remota and whose structure was established by spectroscopic evidence, was inactive.