Objectives:The study aim to determine the factors affecting the saliva pH of the urban and rural children in the Philippines in relation to their oral health. Methods:A total of 200 children aged 6-12 years old from an urban and rural community were randomly selected ,based on the criteria set by the researchers,interviewed and examined. Questionnaires used covered their personal characteristics, oral health practices and diets. Clinical examination were undertaken to record DMF index and sample of saliva were collected to determine its pH. Results: Urban children had better oral hygiene practices and their diet are mostly comprised of acidic foods .The pH level of saliva of the Urban Children 26% acidic, 54% neutral and 20% alkaline and rural children 15% acidic 48% neutral 37% alkali; and DMF index is 35 (urban) and 28.33(rural). Conclusions: Diet of a child affects the pH of the saliva which could contribute to the formation of caries. Good oral hygiene practices alone is not sufficient to prevent caries formation