The aim of the present study was to compare changes in salivary pH after intake of apple juice and its various dilutions with mineral water, in children and adults. 15 children (mean age 4.4 ± 0.9 years), and 15 adults (mean age 30 ± 2.4 years) participated in this study. Carbonated mineral water, apple juice and its various dilutions with carbonated mineral water were tested. The pH-value of unstimulated whole saliva was measured at the same time of day. The pH-value was measured again immediately after intake of a beverage, and 5, 10, 15 and 25 min later. The flow rate and buffering capacity of stimulated saliva, and the buffering capacity, calcium and phosphorus contents of the beverages were measured. The statistical evaluation of the data was performed employing the Wilcoxon test for paired samples. The mean base value of the pH of whole saliva was 7.0 ± 0.2 (children), and 6.8 ± 0.3 (adults). The differences in the flow rates of stimulated saliva in children and adults were statistically significant (p = 0.0003). The intake of mineral water led to a statistically significant rise in the salivary pH-value (p 0.05). Undiluted and diluted apple juice caused a reduction in the salivary pH-values. Within the first 10 min the changes of pH in saliva only differed significantly between mineral water and the other beverages (p 0.01). In the pH range of 5.8 - 7.0, mineral water had a weak buffering capacity, while undiluted apple juice had a high buffering capacity. With regard to dental and general health, only mineral water can be recommended for children. Keywords: apple juice, salivary pH, children, adults