Malaria is one of the most widespread parasitic diseases. It is caused by Plasmodium protozoa. Plasmodium falciparum infection leads to the most virulent symptoms in human. Researchers have been devoted to develop a malaria vaccine for malaria eradication, especially against P.falciparum. Rhoptry associated protein-1 (RAP-1) is one of the P.falciparum vaccine candidates because it protected monkeys in an immunization experiment and some monoclonal antibodies raised against this protein can inhibit parasite growth in vitro. This thesis describes work in which the epitopes of the inhibitory monoclonal antibodies were mapped by using a combination of recombinant DNA technology and peptide synthesis. The part of the rap-1 gene, which contains epitope of inhibitory monoclonal antibodies, was subcloned and expressed in Escherichia coli in a β-galactosidase fusion form. The use of restriction enzymes and exonuclease III to generate different fragements of rap-1 gene suggested that the epitopes of these monoclonal antibodies cluster near a proteolytic cleavage site on the protein (between A_190 and D_191). This was confirmed when the epitope of all the inhibitory monoclonal antibodies were located on a TLTPLEELYP_210 peptide generated as one of a series of overlapping decapeptides. The study of RAP-1 protein immunogenicity in rabbit and humans showed that both species are also able to recognize this 'inhibitory epitope'. The epitope mapping of another set of monoclonal antibodies raised against a recombinant RAP-1 protein lacking its 'native' conformation was carried out. The results suggested that this expressed protein can stimulate immune response against the 'inhibitory epitope' but two additional epitopes are also recognized by these monoclonal antibodies. Sequence analysis of the rap-1 gene from a number of isolates and clones demonstrated that the RAP-1 protein is highly conserved in P. falciparum from several parts of the world. This finding verified the potential of the RAP-1 protein as a malaria vaccine candidate.