The hypomaturation-hypoplasia type of Amelogenesis imperfecta with taurodontism is a rare condition. All previously documented cases have featured clinically involved teeth in successive generations. A family is presented in which the son was affected clinically and radiographically, whereas the teeth of his sister and mother were clinically normal but radiographically had the taurodont morphology. Molars extracted from the boy showed both hypoplasia and hypomineralisation on histopathological examination. It is proposed that the taurodont tooth form in the sister and mother represents a partial manifestation of the condition.