DNA methylation of tumor suppressor gene promoters is the most frequent phenomenon leading to inactivationof function, consequently driving malignant cell transformation. Cyclin D2 is implicated in tumor suppression.In our study, we carried out the MSP assay to evaluation the methylation status at CpG islands in the cyclinD2 promoter in breast cancer cases from the Vietnamese population. The results showed that the frequency ofmethylation reached 62.1% (59 of 95 breast cancer tumors), but was low in non-cancer specimens at 10% (2 of20 non-cancer specimens). Additionally, with an RR (relative risk) and OR (odd ratios) of 6.21 and 14.8, DNAhypermethylation of cyclin D2 increased the possibility of malignant transformation. Our results confirmed thecyclin D2 hypermethylation could be used as the potential biomarker which could be applied in prognosis andearly diagnosis of Vietnamese breast cancer patients.