The aims of the study: caries experience assessment in adult patients with dental fluorosis living in endemic area and in the region with normal fluoride concentration in drinking water; assessment of correlation between DMFT index and elementary composition of mixed saliva in adult patients with dental fluorosis. Materials and methods. Two groups of patients took part in the clinical study. Group 1 involved 33 persons with dental fluorosis living in endemic area. In group 2 there were 31 persons with dental fluorosis living in region with normal fluoride concentration in drinking water. DMFT index was calculated. Enamel resistance to acids and remineralizing activity of saliva were tested. Electron probe X-ray microanalysis (EPXMA) was used to detect elementary composition of mixed saliva. Results. The mean DMFT value was 3.97±0.31 in group 1 and 4.65±0.41 in group 2, which was 15% higher. In both groups high enamel resistance to acids was observed, but remineralizing activity of saliva was significantly better in group 1. The mean fluoride concentration in mixed saliva was 42% higher in group 1 comparing to group 2 (0.108±0.003 mass%, and 0.063±0.0002 mass%, respectively). Conclusion: Adult patients with dental fluorosis living in endemic area are more caries resistant comparing to those living in region with normal fluoride concentration in drinking water. It’s associated with elevated fluoride concentration in mixed saliva due to permanent fluoride consumption with drinking water.