Objective: To estimate the prevalence and severity of molar incisor hypomineralization (MIH) in 8 years old children living in an endemic fluorosis area. Methods: MIH prevalence rate was determined from a study sample comprising 613 participants. They were recruited from 11 urban public schools with similar socio-economic status. Oral evaluations were performed and diagnosed MIH teeth were classified under Ghanim et al.'s criteria. Statistical descriptive and comparative analyzes were carried out. Results: First permanent molars were the tooth group most affected, followed by the upper central incisors, lower central incisors, lower lateral incisors, and upper lateral incisors. There was no significant statistical difference by gender and by maxillary/mandible arches (P = 0.82 and 0.26, respectively). The frequency of MIH was more in molars compared to incisors (P < 0.02). Conclusions:The MIH prevalence in this study was 12.4 percent. According to the MIH severity, degree 2 was the most frequently detected (76.4 percent).