Objective:To investigate the antimalarial potential of kolaviron(KV), a biflavonoid fraction from Garcinia kolaseeds, againstPlasmodium berghei(P. berghei) infection inSwiss albino mice. Methods:The study consists of seven groups of ten mice each.GroupsⅠ,Ⅱ and Ⅲ were normal mice that received c oil,KV1 and chloroquine(CQ), respectively.GroupsⅣ,Ⅴ,Ⅵ and Ⅶ were infected mice that received c oil,CQ,KV1 andKV2, respectively.CQ,KV1 andKV2 were given at10-,100- and200-mg/kg daily, respectively for three consecutive days.Results:Administration ofKV1 andKV2 significantly(P<0.05) suppressedP. berghei-infection in the mice by85% and90%, respectively, whileCQ produced87% suppression relative to untreated infected group after the fifth day of treatment.Also,KV2 significantly(P<0.05) increased the mean survival time of the infected mice by175%.The biflavonoid prevented a drastic reduction inPCV from day 4 of treatment, indicating its efficacy in ameliorating anaemia.Significant(P<0.05) oxidative stress assessed by the elevation of serum and hepatic malondialdehydewere observed in untreatedP. berghei-infected mice.Specifically, serum and hepatic malondialdehyde levels increased by 93% and78%, respectively in the untreated infected mice.Furthermore, antioxidant indices, viz; superoxide dismutase, catalase, glutathione-s-transferase, gluathione peroxidase and reduced gluathione decreased significantly(P<0.05) in the tissues of untreatedP. berghei-infected mice. KV significantly(P<0.05) ameliorated theP. berghei-induced decrease in antioxidant status of the infected mice.Conclusions:This study shows that kolaviron, especially at200 mg/kg, has high antimalarial activities inP. berghei-infected mice, in addition to its known antioxidant properties.