OBJECTIVE To evaluate the effect of cow's milk, milk plus sugar, milk plus honey and formula on plaque pH when compared to a 10% sucrose solution in 8- to 12-year-old children. METHODS Plaque pH was measured using a pH microelectrode at baseline to determine resting plaque pH and at intervals between 1 and 60 min after rinsing with the test liquids. Plaque pH data were analysed using repeated- measure ANOVA and paired t tests. RESULTS The study findings showed that 10% sucrose has the greatest cariogenic potential, followed by milk plus honey, milk plus sugar, formula and cow's milk. Except for the control group, the evaluated foods did not reduce the pH below 6. CONCLUSIONS Although the test groups appear to be non-cariogenic as compared with sucrose, they still lead to considerable acidogenic response in the dental plaque. When bottle feeding is essential, it was confirmed that frequently use of these beverages may cause enamel demineralisation.