Regional odontodysplasia is a localized disorder of tissues of dental origin resulting in characteristically bizarre clinical and radiographic appearances. It most commonly affects the maxillary anterior teeth of both the permanent and primary dentitions. The authors present a worldwide bibliography of reported cases and discuss the suggested theories regarding the condition's etiology. Although the majority of cases of regional odontodysplasia must be regarded as idiopathic, various developmental anomalies may produce identical changes in the teeth in one or more quadrants. A number of previously reported cases are also reconsidered with regard to their diagnosis and guidelines are suggested for the treatment of patients affected by regional odontodysplasia.