BACKGROUND & OBJECTIVES:Despite continuous global attempts to fight parasitic infections, malaria still remains one of the major human life threatening diseases. Difficulty of producing efficient antimalaria vaccines and increasing drug-resistant strains, highlight the urgent need to search for a new alternative antimalaria drug. The aim of this study was to find a new agent against malaria parasite with maximum efficacy and minimum range of side-effects. For this, the antiplasmodial activity of commercial chitosan, a natural carbohydrate polymer, was evaluated on Plasmodium berghei via in vivo experiments. This is the first report that to highlight antimalarial effects of low molecular weight chitosan against P. berghei in vivo. METHODS:Low molecular weight chitosan with 95% degree of deacetylation was melted in normal saline with 1% (w/v) acetic acid for preparing 10, 20, 40 and 80 mg/kg concentrations of chitosan, which were then examined for their antimalarial efficacy in P. berghei infected mice. RESULTS:The study showed that differrent concentrations of chitosan exhibited significant antimalarial effect (p= 0.002) when compared with the control group. Also, analysis of mice survival time showed significant differences between 20 and 80 mg/kg concentrations of used chitosan in comparison to negative control group. INTERPRETATION & CONCLUSION:The results of this study showed that the chitosan has potent antimalarial activity and could be suggested as an alternative antimalarial drug component.