Molar-incisor hypomineralization(MIH) is a type of enamel hypomineralization that is defined as hypomineralization of the systemic origin of one or more permanent first molars, which are frequently associated with affected incisors. The prevalence varies largely because of diagnostic criteria, number of people, age, and different countries and regions. To date, the etiology is unknown, but MIH is generally related to systemic conditions or environment during the child’s first three years and now also considered related to genetics. The main clinical manifestations are color change, enamel breakdown, caries susceptibility, hypersensitivity, and early loss. The most appropriate treatment method should be selected based on the developmental stages of affected teeth and severity. Additional attention should also be given to hypersensitivity and behavior management problem. This article aims to review the prevalence, etiology, characteristic features, clinical presentation, diagnosis, and treatment of MIH.