Understanding the functional role of proteins expressed by is an important step toward unlocking potential targets for the development of therapeutic or diagnostic interventions. The armadillo (ARM) repeat protein superfamily is associated with varied functions across the eukaryotes. Therefore, it is important to understand the role of members of this protein family in biology. The armadillo repeats only (ARO; Pf3D7_0414900) and merozoite organizing proteins (MOP; Pf3D7_0917000) are armadillo-repeat containing proteins previously characterized in . Here, we describe the characterization of another ARM repeat-containing protein in , which we have named the Merozoites-Associated Armadillo repeats protein (PfMAAP). Antibodies raised to three different synthetic peptides of PfMAAP show apical staining of free merozoites and those within the mature infected schizont. We also demonstrate that the antibodies raised to the PfMAAP peptides inhibited invasion of erythrocytes by merozoites from different parasite isolates. In addition, naturally acquired human antibodies to the N- and C- termini of PfMAAP are associated with a reduced risk of malaria in a prospective cohort analysis.