The carboxy-terminus of the major merozoite surface protein of Plasmodium has been shown to be the target of protective immunity in a number of non-vivax malaria parasite species. In an effort to develop a protective vaccine for Plasmodium vivax, the most prevalent form of human malaria, we expressed in Saccharomyces cerevisiae the 19-kDa a carboxy-terminus of Pv200 as a His6-tagged, secreted polypeptide. Five of seven H-2 congenic mouse strains elicited antibodies that recognized yeast produced PV200(19) by ELISA. The vaccine appears to be immunogenic and widely recognized, and to contain one or more helper T cell epitopes that may allow boosting with subsequent natural infections.