The aim of this study was to investigate the relationship between salivary buffer capacity and menarche, and to explore any association with levels of the sex hormone progesterone in stimulated whole saliva in adolescent girls. The material comprised 162 girls, 12 years of age at baseline in the 6th grade, who were followed for 3 years. Every 4th month, a stimulated whole saliva sample was collected, secretion rate and buffer capacity were determined, and information was gathered on menarche, ongoing menses, and caries increment. Once yearly, the salivary concentration of progesterone was determined with an enzyme immunoassay kit. The results showed a significantly impaired salivary buffer capacity over the years (P < 0.05). Low buffer capacity was significantly correlated with low secretion rate (r = 0.42; P< 0.001) and DMFT increment (r=0.20; P<0.05). Pre-menarche buffer capacity did not differ from the postmenarche scores. The concentration of progesterone in saliva increased with age but displayed no significant relationship to buffer capacity, flow rate, or caries increment. In conclusion, the findings of this study suggest that the salivary buffer capacity may be impaired over the adolescent years in females, but the reason remains unclear.