Thrombophilia is a condition that may cause venous obstruction, leading to serious illnesses such as stroke, respiratory failure, and even death. This condition is hereditary or related to the immune system. Inherited thrombophilia is screened by analysing genetic variants (allele). In this study, we analyse 4 variations in 3 genes, which occur at high variable frequency, namely Methytetrahydrofolate Reductase (MTHFR C677T, MTHFR A1298C), Factor V Leiden (FVL C1691T) and Plasminogen Activator Inhibitor 1 (PAI-1 5G/4G), using allele-specific polymerase chain reaction (ARMS-PCR). The primers were designed using FastPCR program and PCR conditions were optimized to identify 8 alleles of 4 variants through 3 multiplex ARMS - PCR reactions. The accuracy of the ARMS - PCR results was confirmed by Sanger sequencing and the real time PCR commercial kit (SNP). Mastering the allele specific PCR technique contributes to the survey of genetic variations in the Vietnamese population in order to screen and treat thrombophilia-related diseases.