Prevalence and severity of dental fluorosis was assessed in 1739 Singaporean children aged 9, 12 and 16 yr in three different ethnic groups. All subjects had resided since birth in Singapore, which has a tropical climate. The water supply was fluoridated in 1957 at a level of 0.7 ppm. In this sample, mouth prevalence was 82.6%, tooth prevalence was 66.9%, the community fluorosis index was at 1.96; 9.2% of children had severe fluorosis and 26.2% had moderate fluorosis. There were no significant gender or racial differences. Prevalences were higher than those reported in most other studies. Due to differences in indices used and methodology, comparisons could not be made directly with other studies.