This study was conducted to screen the antiplasmodial activity of chloroform extracts of Quassia borneensis against different intraerythrocytic cycle of chloroquine-resistant Plasmodium berghei NK65. The antiplasmodial activity was measured using SYBR green I assay for determining the concentration that inhibited 50% (IC50) of the Plasmodium’s activity after 24 hours of treatment (0.0001-100 mg mL-1). All of the extracts showed potent activity against all of the cycles. The trophozoite and schizont stages were considerably more sensitive to the extracts than the ringstages parasites. The values were compared to the controls treated with chloroquine and artemisinin. Hence, the chloroform extracts of roots and bark of Q. borneensis demonstrated potent activities towards each life cycle of chloroquine-resistant P. berghei and has a potential to be developed as an antimalarial agent.