Background : primary school-aged children are very at risk of dental and oral diseases such as dental caries. According to the World Health Organization (WHO) in 2005 showed that 90% of children worldwide experience tooth decay problems. Decrease in saliva pH can be caused by foods containing carbohydrates to make the mouth become acidic so that the formation of bacteria asidogenik. pineapple (Ananas comosus) contain bromelin enzyme that serves as an antibacterial that can inhibit bacterial growth. Research objective : this research is to know the difference of acidity of pH saliva between before and after chewing pineapple fruit (Ananas comosus). Method : the study used a pseudo experimental method with pretest and posttest control group design. Subjects were 31 students. Subject brushing before saliva stabbing. Salivary stomach before and after chewing pineapple fruit (Ananas comosus) as much as 100 grams that is inserted into the saliva pot. Salivary pH measurements using dental pH saliva indicator were then analyzed using a wilcoxon test test. Research result : showed significant differences (P <0.05) between salivary pH before and after chewing pineapple fruit (Ananas comosus).