In Ethiopia, the general population is quite vulnerable to unpredictable cyclicrnepidemics of Plasmodium falciparum malaria. However, there is very littlerninformation on the anti-malaria immune profile of the population residing in thernendemic regions of the country. This study was designed to investigate the nature ofrnhumoral immune response to malaria in two population groups in two endemicrnlocalities, Shewa Robit in the north and Boditi in south. In a cross-sectional study, thernstudy participants were diagnosed for malaria infection microscopically and by thernrapid diagnostic test (RDT). The sera were tested by using enzyme-linkedrnimmunosorbent assay (ELISA) for total immunoglobulin (Ig) G against P. falciparumrnblood-stage vaccine candidate antigens: apical membrane antigen 1 (AMA1),rnglutamate-rich protein (GLURP) R2 region, and merozoite surface protein 2 (MSP2)rnallelic variants (3D7 and FC27) in Shewa Robit. Total IgG against GLURP-R0, MSP3rnand GMZ2 and IgG subclasses against GLURP-R0 and MSP3 were assayed in bothrnShewa Robit and Boditi sera. Whereas 23(8.6%) blood-smear-positive cases for P.rnfalciparum were detected in Boditi, all Shewa Robit study participants had norndetectable P. falciparum infection. At both localities total IgG prevalence and levelsrnto GMZ2 were significantly higher than the response to the component domains (GLURP-R0 and MSP3) indicating the induction of strong GMZ2-specific naturalrnantibodies. There was significant difference between the median antibody level tornGMZ2, GLURP-R0 and MSP3 compared to the responses to other antigens tested inrnShewa Robit, indicating that GMZ2 could be a more relevant blood-stage malariarnvaccine candidate antigen. Higher total IgG and subclass prevalence and levels wererndetected in Shewa Robit than Boditi, suggesting difference in the intensity of malariarntransmission in the two localities and/or genetic differences between the twornpopulation groups in their response to blood-stage P. falciparum antigens. In bothrnstudy sites, IgG subclass antibody levels to GLURP-R0 were significantly higher thanrnthat to MSP3 for all corresponding subclasses in most individuals, indicating thernhigher relative immunogenicity and protective potential of GLURP-R0 compared tornMSP3. Against both GLURP-R0 and MSP3, the ratio of cytophilic to noncytophilicrnantibodies was >1 in the majority of the study participants, in both study sites,rnindicating the induction of protective antibodies against the two antigens. Analysis ofrnage-related pattern in antibody levels against the antigens tested showed a positivernassociation with increasing age for most antigens suggesting the role of intrinsic agerelatedrnfactors in immune maturation. The age factor appears plausible as there wasrnno evidence for increase in antibody response with increasing frequency of reportedrnpast clinical malaria. Overall, the study has shown that Ethiopian population groupsrnresiding in unstable and seasonal malaria epidemiological settings have a highrnprevalence and levels of long-lived antibodies that readily recognize P. falciparumrnblood-stage vaccine candidate antigens, particularly GMZ2 and its componentrnfractions (GLURP-R0 and MSP3). Furthermore, detection of high level antibodyrnresponses in non-febrile smear-negative individuals without history of reported pastrnmalaria episodes may possibly be an indication of a low-grade, asymptomaticrn(submicroscopic) infections in the induction and maintenance of high level protective rnimmunity. Therefore, to determine the implication of submicroscopic infections in therninduction and boosting of malaria immunity versus the existence of long-livedrnmalaria-specific antibodies in the absence of boosting from submicroscopic infection,rnPCR confirmation of the microscopy-negative samples would be necessary.rnKeywords: antigen, blood-stage vaccine, cytophilic IgG subclass, ELISA, Ethiopia,rnfalciparum malaria, noncytophilic IgG subclass