Background: The inactivation of RASSF1A, which caused by promoter hypermethylation, has been reported to be the etiological factor of nasopharyngeal carcinoma in previous studies. However, there was no study carried out to evaluate the status of RASSF1A in Vietnamese NPC patients. Aims: This study was designed to identify and evaluate the hypermethylation frequency of the RASSF1A promoter in nasopharyngeal biopsies as well as the association between hypermethylation of RASSF1A and nasopharyngeal tumorigenesis from Vietnamese NPC patients. Materials and methods: Seventy NPC biopsy samples and seventy non-cancerous swab specimens were collected from the local hospital and analyzed by the Nested-MSP method. Results: The frequency of RASSF1A gene hypermethylation was markedly higher in NPC biopsy samples, counting for 67.14%, compared to non-cancerous samples, counting for 12.86%. A trend toward positive association was found between hypermethylation of the RASSF1A gene and nasopharyngeal carcinoma. The hypermethylation of RASSF1A was significantly associated with an approximately 13.85 fold increase in NPC compared to non-cancerous samples. Moreover, hypermethylation of RASSF1A was found to be correlated with the clinical stage and pathological classification. Conclusion: Our data suggested that the hypermethylation of the RASSF1A gene promoter is significant in nasopharyngeal carcinoma in Vietnamese patients. The hypermethylation of RASSF1A may be a potential biomarker for NPC in the Vietnamese population.