Background: Saliva is a complex fluid produced by salivary glands. The function of saliva is maintaining an environment of the mouth. Saliva has an important role in the caries process in which the saliva pH 5.5 at a process of tooth demineralization or dental caries. One function of saliva is buffering where the buffering capability can withstand lower pH or increasing oral acid it is also related to the viscosity or volume. Caries is a disease of hard tissues caused by the interaction of bacteria on the surface of the teeth, plaque or biofilm and diet especially carbohydrate component which can be fermented to acid by plaque bacteria, particularly lactic acid. There is four factors that influence the occurrence of caries, (1) time, (2) host, or teeth, (3) microorganisms, and (4) substrate. The aim of this study was conducted to determine the influence of pH buffer capacity of saliva and caries status of children aged 6-12 years. The method used in this study is a clinical observation. A number of respondents are 10 children from the patient's Oral and Dental Hospital of Universitas Muhammadiyah Yogyakarta. The Result is significance α value def-t (p=0.360) and DMF-T (p=0.385) based on analysis of the correlations statistical test. Therefore the conclusion is there is no significantly between the pH of the saliva and the caries status of 6-12 years old children in the mixed tooth period.