Dental caries is the major dental and oral health problems in Indonesia and world wide. Alteration in the saliva acidity level (pH) in the oral environment plays an important role in dental caries. Red betel leaf (piper crocatum) is a herbal plant that commonly found in Indonesia. Red betel leaf contains alkaloid, flavonoid, tannin and essential oil which have antibackterial activities. Objectives : The aim of this study was to determine the acidity change (pH) of saliva in elderly people with diabetes mellitus type 2 after gargling of 10% boiled red betel leaves.Methods : the subjects of this study were 30 persons who divided randomly into two groups i.e treatment group and control group. Each group consisted of 15 persons. In the treatment group, the subjects gargled using 10% boiled red betel leaves, while in the control group the subject gargled using aquades. The saliva was collected on each time treated and followed by pH measuring. The data analysis was conducted by Independent t-test statistic (p≤0,05).Results : the results showed that there was an effect of increasing salivary acidity (pH) of saliva after gargling boiled of red betel leaf (Piper crocatum) in elderly people with diabetes mellitus type 2. Conclusion : The change of acidity level (pH) of saliva was increased significantly at 5th to 15th minute from 5.33 to 6.67 after gargling boiled red betel leaves concentration of 10%. The acidity level range stated above indicates a normal. Key words : pH of saliva, red betel leaves, elderly, diabetes mellitus type 2