The merozoite surface protein 1 (MSP-1) is expressed in all Plasmodium species and is considered a major malaria vaccine candidate. We found that MSP-1 from Plasmodium vivax ( Pv MSP-1) contains a region of significant sequence homology with the 190L subunit vaccine derived from the P. falciparum MSP-1. The fragment, termed Pv 200L, was expressed as a recombinant protein in Escherichia coli (r Pv 200L) and used to asses its immunologic relevance as a vaccine target. A cross-sectional, seroepidemiologic study conducted in Buenaventura, Colombia showed that 52.2% (95% confidence interval [CI] = 39.8–64.3) of individuals previously exposed to P. vivax and 72.8% (95% CI = 61.8–82.1) of P. vivax –infected patients had IgG antibodies to r Pv 200L. Immunization of BALB/c mice and Aotus monkeys induced IgG antibodies (titer > 10 6 ) that cross-reacted with P. vivax parasites. Immunized monkeys displayed partial protection against a challenge with P. vivax blood stages. Our results suggest that Pv 200L is a new malaria vaccine subunit and deserves further testing.