OBJECTIVE: To assess the prevalence of tooth wear in adolescents and its relationship with diet, saliva and gastro-oesophageal reflux. DESIGN: Single centre cluster sample epidemiological study. SETTING: A school in London in the summer of 1996. SUBJECTS: 11-14-year-old schoolchildren. MAIN OUTCOME MEASURES: The Smith and Knight tooth wear index (TWI), salivary factors, diet and symptoms of gastro-oesophageal reflux were recorded for all subjects. RESULTS: Results were obtained from 210 subjects. One subject refused to provide a saliva sample and 11 subjects provided insufficient saliva for analysis of buffering power (n = 198). 57% (95% confidence intervals 50.3-63.7%) of subjects had tooth wear on more than ten teeth and a median 12% (interquartile range 6-18%, 95% confidence intervals 8-14%) of surfaces were affected. However, dentine involvement was rare. The median intake of carbonated drinks was 2 cans (interquartile range 1-3) a day. However, there was no correlation with TWI (r = -0.09, P = 0.19). There was no relationship between tooth wear index (TWI) and salivary flow rate (r = -0.02, P = 0.78) or buffering capacity (r = -0.02, P = 0.76). A trend was observed for those with a reported history of regurgitation (n = 27) to have a higher maxillary TWI (median 8, interquartile range 2-13) compared with those who did not (5, 2-9, P = 0.06). CONCLUSIONS: Tooth wear is common in adolescents and the relationship with dietary acid, salivary buffering and symptoms of gastro-oesophageal reflux is complex and requires further investigation.