The objective of this paper was to compare the DEAN, T-F and TSIF dental fluorosis indexes in relation to prevalence of surfaces, teeth and locality, and to verify the statistical correlation among them. The sample consisted of 461 schoolchildren, ages 12-14 years, born and reared in 3 cities in the State of São Paulo from 2 years of age. A total of 153 were from Cesário Lange with a fluoride concentration in the water supply of 1.4 ppm F, 142 from Piracicaba (0.7 ppm F) and 166 from Iracemápolis (< 0.3 ppm F). The clinical examination was conducted after tooth brushing, using a plane mirror, artificial light and air drying of the teeth for 1 min. Premolars, second molars, and occlusal surfaces were the most severely affected. The three indexes showed similar percentages of children affected in the 3 three cities: 32.7%, 16.9% and 4.2% for the DEAN index, 33.3%, 17.6% and 4.2% for the T-F index and 32.7%, 16.9% and 4.2% for the TSIF index. There were no difficulties in using the three indexes in the field trials; thus the use of any one may be recommended in regions with similar fluoride concentrations to those of this study.