In the present study of antimalarial efficacy, aqueous extracts of leaves and unripe fruits of Psidium guajava, leaves of Ocimum sanctum and leaves of Murraya koenigii are evaluated against Plasmodium berghei (chloroquine resistant NK65 strain) infected white albino BALB/c mice. A 7 days oral administration was adopted with different dosage viz., 350 mg, 750 mg and 1,000 mg/kg body weight as treatment schedule along with parasite (Group I) and drug control with Chloroquine, 50 mg/kg body weight (Group II). All the parts were extracted based on the decoction method, which is commonly seen among the villagers/tribes as their usual method of preparation of decoction for most of the ailments. The antimalarial activities were evaluated from the giemsa stained blood smears collected from different treated groups of mice used in this experiment. The antiplasmodial effect that is percent parasitaemia and percent suppression (values in parenthesis) showed by the treated groups of mice at 350 mg/kg b. wt. by the aqueous extracts of P. guajava leaves (Group III) was 19.8 ± 1.22 (73.7 %), P. guajava unripe fruits (Group IV) was 52.7 ± 2.19 (30.0 %), leaves of O. sanctum (Group V) was 64.0 ± 0.73 (15.1 %) and leaves of M. koenigii (Group VI) was 28.9 ± 0.81 (61.6 %) whereas at 750 mg/ kg b. wt., it all showed 10.3 ± 0.7 (80.2 %), 26.3 ± 0.52 (65.1 %), 42.0 ± 0.47 (44.2 %) and 14.9 ± 0.46 (71.5 %) whereas at 1,000 mg/kg b. wt. dose, it all showed 9.2 ± 0.39 (85.8 %), 25.6 ± 0.40 (62.0 %), 41.8 ± 0.29 (35.5 %) and 14.0 ± 0.42 (76.9 %) respectively. Keywords Medicinal plants ÁIn vivo antimalarial bioassay Á Mice Á P. berghei