Merozoite surface protein:3 α ofplasmodium vivax(PvMSP:3 α) was a kind of protein with molecul ar weight ranging from 148 to 150kD during asexual stage inside the red blood cells.PvMSP:3 α contained an a laninE-rich central domain and a series ofheptad repeats which were important structure predicted to form a coi led:coil tertiary peptide structure.The present study had shown that PvMSP:3 α was highly genetic polymorphi sm both in high and low malaria endemic area around the world.A large number ofpolymorphic loci was not spr ead in the whole PvMSP:3 a gene but mainly limited to some discontinuous coding regions.Sequences on Block Ⅰ (N: terminal) were polymorphisms but Block Ⅱ (C: terminal) were conserved of the alaninE-rich central dom ain.At present,PvMSP:3 a had been used as a suitable molecular marker to genotyping and epidemiological stu dy ofplasmodium vivax.PCR:RFLP displayed a variety ofgene types ofPvMSP:3 a from different countries an d regions.According to the different PCR fragment length,PvMSP:3 a was divided into four genotypes which were Type A(1900~2000 bp),Type B(1400~1500 bp),Type C(1100~1200 bp) and Type D(300~500 bp).Type A was the most proportion of four genotypes and Type C was the most conservative of four genotypes.Type A,B a nd C had also been found in Chinese population except Type D.In addition to single infection,mixed genotypes infection also existed in some areas around the world.Moreover,PvMSP:3 a was an important candidate antige n for development of malaria vaccines.The purpose of this review is to summarize research progress on the mol ecular structure,gene polymorphism and genotyping of PvMSP:3 α.