Objective: To investigate the effect of soft drink on human salivary pH. Methods: Thirty healthy volunteers were included in this study. Cola, orange or lemon soft drinks were consumed (200 ml per day) by each participant for 3 days. Saliva was collected 10 min before drinking, immediately after, and at 30 and 60 min after drinking, and the pH of the saliva was measured. Results: The pH of saliva collected immediately and 30 min after the consumption of all three types of drink was significantly lower than that of saliva collected before consumption (except for the lemon group between before and 30 min after consumption). There is no pH difference between the saliva collected before and 60 min after consumption of the three drinks (P > 0.05). Conclusion: Soft drink intake can reduce salivary pH. Therefore, frequent consumption of soft drinks could be a high risk for dental erosion. Keywords: saliva, pH, soft drink