Abstract: Humoral response exhibited by a fraction of Plasmodium berghei is evaluated in the present study. Immunization of mice with S fraction (supernatant of 20,000 rpm centrifugation) of Plasmodium berghei exhibited high humoral immune response. S fraction contained proteins of molecular weight ranging from 23.15-205.00 kDa. The humoral response was serodiagnostically analyzed employing ELISA, IFA and in vitro invasion inhibition assays. Antimalarial antibodies significantly inhibited invasion of Plasmodium berghei in short-term invasion assay. From the in vitro culture study it was found that S fraction exhibits a high humoral response and sera of five out of ten immunized mice inhibited more than 50% of invasion of erythrocytes by P. berghei.