In an epidemiologic study in the middle of Sweden comprising 425 000 children age 3-19 yr, 105 children were diagnosed as having hereditary amelogenesis imperfecta (HAI). The material then was primarily classified upon clinical criteria into different subgroups either associated to a hypoplastic or to a hypomineralized type of HAI. Analyzing available genetic data obtained from 95 children in 76 families and further 11 adults in 10 families, eight different entities of HAI could be identified in a classification of HAI. In both of the basic types of HAI, the hypoplastic and the hypomineralized, autosomal dominance was the most common mode of inheritance, even if an autosomal recessive inheritance could be identified in some of the subgroups of HAI. The hypoplastic type (rough-pitted), autosomal dominance with incomplete penetrance was dominating in the material, 47 out of 105 cases. The clinical classification seemed to be relevant when testing the material on a genetic basis showing that the clinical criteria provide a strong support for a classification of HAI.